CN115411770A - Energy management method of renewable energy system - Google Patents
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- H—ELECTRICITY
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- 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
- H02J15/00—Systems for storing electric energy
- H02J15/008—Systems for storing electric energy using hydrogen as energy vector
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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
- H02J3/008—Circuit arrangements for ac mains or ac distribution networks involving trading of energy or energy transmission rights
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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
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
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- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0025—Sequential battery discharge in systems with a plurality of batteries
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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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
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- 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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- 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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- 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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- 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
- H02J2300/28—The renewable source being wind 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/30—The power source being a fuel cell
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- 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
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Abstract
The invention discloses an energy management method of a renewable energy system, which comprises the following steps: s1, detecting sampling signals of all modules of a renewable energy system, and judging whether all the modules except a power grid module in the renewable energy system normally operate or not; step S2, maximum power tracking: tracking the maximum output power of the photovoltaic module and the wind energy module, determining whether to start the electrolytic cell module according to the relation between the total power of the photovoltaic module and the wind energy module and the load power, and performing equalizing charge on the lithium battery pack module; s3, judging the running state of the power grid module: determining a load power supply mode according to the running condition of the load power supply; and S4, calculating the yield of hydrogen production by water electrolysis by using the peak valley, and determining whether to start the electrolytic cell. The method can realize the maximum economic benefit operation of the system on the basis of ensuring the long-term stable operation of the system, and realize the reasonable scheduling of the steady-state operation and the fault operation of the hydrogen-containing energy storage renewable energy system or the micro-grid.
Description
Technical Field
The invention relates to the technical field of energy management, in particular to an energy management method of a renewable energy system.
Background
With the increasing economic growth, social progress and population increase, the global energy demand is increasing. Non-renewable energy sources such as coal, petroleum, natural gas and the like occupy an important position in the global national energy consumption structure, so that the reserves of the non-renewable energy sources are greatly reduced, and the energy exploitation and consumption are extremely unbalanced. Meanwhile, the utilization of fossil energy also causes serious environmental pollution, and the greenhouse effect, haze and the like are increasingly intensified, so that the life of people is influenced. With the ever-increasing demand for electricity, large power grids have rapidly developed with the powerful advantages they represent. However, the operation cost and difficulty of the traditional large power grid are increasing, and the disadvantages of the traditional large power grid are also appearing increasingly. At present, the distributed power generation technology is vigorously developed, and renewable energy is fully utilized to become a main way for solving the problem of future energy. China has developed renewable energy medium-long term development planning, and provides guarantee and policy support for distributed power generation related technologies represented by photovoltaic power generation and wind power generation from the legislation perspective, so that the utilization of renewable energy is promoted to the strategic height. The distributed power generation technology can fully utilize energy resources in various places, and is flexible, economic and environment-friendly. But on the other hand, a large number of distributed power sources, dispersed, are not controllable for a large grid. After the capacity permeability of the distributed power source reaches a very high value, it is also a greater challenge to achieve reliable operation of the power distribution system and guarantee the power quality of users.
In order to alleviate the contradiction between the distributed power supply and the traditional large power grid, the micro-grid technology has attracted more attention. The micro-grid is a single controllable unit which consists of various distributed power supplies, an energy storage system, a load and a control device and can realize self control and management. Under normal conditions, the system works in a grid-connected mode, the system is connected with a large power grid through a contact point, when the power quality of the power grid does not meet requirements or fails, the PCC is disconnected, and the micro-grid system can operate in an island mode to continuously supply power to important loads carried by the micro-grid system. The micro-grid is used as a connecting junction of the distributed power supply and the power distribution network, so that adverse effects on power supply reliability and power quality brought by the micro-grid are reduced, meanwhile, renewable energy sources can be fully utilized, and the energy utilization rate is improved.
Under the background of the national strong advocation of green energy development, the energy internet is widely concerned, and wind power and photovoltaic power generation become research hotspots as main forms of new energy power generation. However, the intermittent and fluctuating output power causes fluctuation, the micro-grid power supply is influenced, the output electric energy quality of the system is influenced, and the key point for solving the problem lies in the matching with the energy storage system. The generation, storage and conversion of hydrogen energy are important links of energy internet, the hydrogen energy storage is concerned about with the advantages of cleanness, high efficiency, high energy density and the like, and the research of using the electrolysis bath-hydrogen storage tank-fuel cell circulating system as an energy storage unit has engineering practice guidance value.
The energy system of the current renewable energy system has the following defects: the energy distribution is not reasonable enough, so that the system reliability is poor; the system module is not comprehensive and economical, and energy waste exists.
Disclosure of Invention
The technical problem to be solved by the invention is to provide an energy management method of a renewable energy system, which can realize the maximum economic benefit operation of the system on the basis of ensuring the long-term stable operation of the system, and realize the reasonable scheduling of the steady-state operation and the fault operation of the renewable energy system containing hydrogen energy storage or a microgrid.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method of energy management for a renewable energy system, comprising the steps of:
s1, detecting sampling signals of each module of the renewable energy system: the renewable energy system comprises a photovoltaic module, a wind energy module, a power grid module, a fuel cell module, an electrolytic cell module, a lithium battery pack module and a hydrogen storage tank, and is used for judging whether other modules except the power grid module in the renewable energy system normally operate or not, stopping operation or leaving the power grid if the modules except the power grid module in the renewable energy system detect a fault, and performing the step S2 if the modules do not have the fault;
step S2, maximum power tracking: maximum output power P to photovoltaic module Light (A) Maximum output power P of wind energy module Wind power Tracking if the maximum output power P of the photovoltaic module is judged Light (es) And the maximum output power P of the wind energy module Wind power Total power P of the sum General assembly Whether or not it is greater than the load power P Negative pole If P is General assembly ≤P Negative pole Then go to step S3, if P is General assembly ＞P Negative pole Supplying power to the load, starting the electrolytic cell module to produce hydrogen, and uniformly charging the lithium battery pack module until the hydrogen storage tank and the lithium battery pack module are full, and selling the residual power;
s3, judging the running state of the power grid module: detecting the sampling signal of the power grid module collected in the S1, judging whether the power grid module operates normally, if not, starting a lithium battery pack to discharge in a balanced manner, and supplying power to a load together with the photovoltaic module and the wind power module; if the judgment result is yes, the power grid is connected or the fuel cell module is started, the photovoltaic module and the wind power module are used for supplying power to a load, and the step S4 is carried out;
s4, calculating the yield of hydrogen production by water electrolysis by using peak valley: judging whether the power consumption peak valley is present at the moment, and if not, continuing to judge after unit time t; if the judgment result is yes, the yield of hydrogen production by water electrolysis in the peak valley is calculated, and the yield calculation formula is as follows: the yield = value of produced hydrogen energy-hydrogen energy conversion cost; judging the calculation result, and starting the electrolytic cell module to produce hydrogen when the peak-valley yield is greater than the electricity consumption until the hydrogen storage tank is judged to be full; and if the peak-valley electrolysis yield is not greater than the electricity fee, not starting the electrolytic cell module.
The technical scheme of the invention is further improved as follows: the step S2 of equalizing charge of the lithium battery pack module comprises the following steps:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, the SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is sequenced from large to small, and charging is started from the first lithium battery cluster;
step b, judging whether the SOC of the 2 nd battery cell in the lithium battery cluster is equal to the minimum SOC of the SOCs of the N battery cells in the lithium battery cluster min If yes, accessing 3 rd to Nth batteries for charging, and if not, returning to the previous step of circulation;
step c, judging whether the SOC of all the N batteries is 1 so as to judge whether the batteries are fully charged, if not, returning to the step a to continue balancing, if so, proving that the charging balancing is finished, and cutting off the lithium battery clusters which are charged;
and d, repeating the step b and the step c, and charging the next lithium battery cluster until all the lithium battery clusters in the lithium battery pack module are charged.
The technical scheme of the invention is further improved as follows: the step of the lithium battery pack module in the step S3 is as follows:
step A, detecting the SOC of each battery monomer in the lithium battery pack module, and judging that a single battery or a plurality of battery monomers in the lithium battery pack module are in an inconsistent state when the difference between the SOC of each battery monomer and a standard value is more than 0.005;
and step B, reconstructing according to the maximum SOC output in the lithium battery pack module through a dynamic programming algorithm, so that the charge states of all the single batteries can tend to be consistent in the discharging process, and all the single batteries in the lithium battery pack module complete the discharging process at the same time.
The technical scheme of the invention is further improved as follows: the dynamic programming algorithm in the step B comprises the following specific steps:
b-1, designing a data structure required by a dynamic programming algorithm: array v [ n ]]Storing the SOC of n batteries, wherein the number of the batteries connected into operation every time is W, and the array C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery is accessed to operate or not;
step B-2, initialization: array C [n+1][W+1] Row 0 and column 0 of (1) are all set to 0;
step B-3, a cycle stage: determining the optimal value obtained under the condition that the previous i batteries can be accessed to operate according to the following formula;
taking n batteries and 1 battery cluster for discharging as an example, for a single battery i, the SOC is v i ；
For any one cell x i Is "x" as a decision i =1 or x i =0", i =1,2, \ 8230;, n, for x i-1 After decision, sequence (x) 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i The problem is in one of two states:
(3) When the battery accessed by the battery cluster reaches the upper limit and the battery i is not allowed to be accessed continuously, x i =0, SOC of battery cluster is not increased;
(4) The battery cluster can be accessed to the battery i, then x i =1, increase in SOC of Battery Cluster v i ；
In the above two cases, the maximum value of the SOC of the battery cluster is x i The value after decision making;
let C [i][j] Representing subproblems
Of optimum value, i.e.
Then the
Indicating a sub-problem of equalizing charge or discharge of a battery
If i =0 or j =0, let C [0][j] ＝C [i][0] ＝0,1≤i≤n,1 is not less than j not more than W, if j<w i The ith battery must not be accessed, i.e. x i =0, then
If the ith battery is switched on for operation, i.e. x i =1, then
Whereby when j ≧ w i When, C [i][j] Taking the maximum of the two, i.e.
The recursive definition of the optimum value thus obtained is as follows:
C [0][j] ＝C [i][0] ＝0
when i =1, calculate C [1][j] ，1≤j≤W；
When i =2, calculate C [2][j] ，1≤j≤W；
……
When i = n, calculate C [n][W] At this time, C [n][W] Is an optimal value;
b-4, positioning the batteries, determining the access state of each battery, and determining the access state of each battery according to the battery position C [n][W] Is pushed forward, if C [n][W] >C [n-1][W] If yes, then indicating the nth battery access operation, x n =1; otherwise, the nth battery is not accessed, x n If =0, the first n-1 batteries are accessed into the battery cluster with the number of the batteries W, and so on until it is determined whether the 1 st battery is accessed for operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] X, which indicates that the ith battery is not in access operation i ＝0；
If C [i][j] >C [i-1][j] Explanation of ith battery access operation, x i ＝1。
The technical scheme of the invention is further improved as follows: when the electrolytic cell module or the fuel cell module or the lithium battery pack module is judged to be in the running state in the steps S2, S3 and S4, controlling the working state of the electrolytic cell module, the fuel cell module and the lithium battery pack module in running according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen gas use charge, the electrolytic cell module is in a lower power output state, the fuel cell module is in a maximum power output state, and the lithium battery pack module is in a low-power charging state; when the electricity charge is lower than the hydrogen gas use charge, the electrolytic cell module is in a maximum power output state, the fuel cell module is in a lower power output state, and the lithium battery pack module is in a high power charging state.
The technical scheme of the invention is further improved as follows: when the electrolytic cell module or the fuel cell module is judged to be in the operation state in the steps S2, S3 and S4, controlling the heat management when the electrolytic cell module and the fuel cell module operate according to the electricity cost and the hydrogen use cost: providing heat for the fuel cell module to reach the optimal working temperature when the electricity cost is higher than the hydrogen gas use cost; when the electricity cost is lower than the hydrogen gas use cost, heat is provided for the electrolytic cell to reach the optimal working temperature.
Due to the adoption of the technical scheme, the invention has the technical progress that:
1. the invention designs an energy management method suitable for a renewable energy system or a microgrid, which can realize the maximum economic benefit operation of the system on the basis of ensuring the long-term stable operation of the system and realize the reasonable dispatching of the steady-state operation and the fault operation of the renewable energy system or the microgrid containing hydrogen energy storage. Compared with the traditional energy management strategy method, the energy management method of the comprehensive energy system provided by the patent considers the energy management of hydrogen energy storage, wherein the energy management comprises the energy management of an electrolytic cell, a fuel cell and a hydrogen storage tank, and the comprehensive energy system has wider applicability;
2. the invention designs a minimum value triggering and dynamic programming combined algorithm aiming at the problem of charge-discharge balance of the lithium battery pack, combines minimum value triggering control with the innovativeness of the dynamic programming algorithm, and adopts minimum value triggering in the charging process; and in the discharging process, a dynamic programming algorithm is adopted to solve the optimal battery pack configuration, so that the discharge capacity of the battery pack is maximized, the redundant batteries are fully utilized, the battery packs are balanced quickly and in a small number of switching actions under the condition of inconsistency, and the maximum discharge capacity of the battery packs is realized.
Drawings
FIG. 1 is a schematic diagram of the architecture of the renewable energy system of the present invention;
FIG. 2 is a schematic diagram of a method of energy management of the renewable energy system of the present invention;
fig. 3 is a process diagram of the energy management method of the energy storage module of the invention.
FIG. 4 is a schematic view of a battery pack structure
Detailed Description
The present invention will be described in further detail with reference to the following examples:
as shown in fig. 1, the renewable energy system includes a photovoltaic module, a wind energy module, a power grid module, a fuel cell module, an electrolytic cell module, a lithium battery pack module and a hydrogen storage tank, wherein electric energy generated by the photovoltaic module and the wind energy module supplies power to a load, when the total power generated by the photovoltaic module and the wind energy module is surplus, a part of the electric energy is converted into hydrogen energy through the electrolytic cell and stored in the hydrogen storage tank, the other part of the electric energy is stored in the lithium battery pack module, and if the total power generated by the photovoltaic module and the lithium battery pack module is surplus, the hydrogen energy is sold; the power grid module is connected to supply power when the photovoltaic module and the wind energy module cannot meet the load power supply, and can determine whether to start the electrolytic cell module to convert the electric energy into hydrogen energy for storage after economic judgment; the fuel cell module and the lithium battery pack module can be used as a standby power supply mode to supply power for the load.
Fig. 2 is a schematic diagram of an energy management method of the renewable energy system of the present invention, and the specific method steps are as follows:
s1, detecting sampling signals of each module of the renewable energy system: judging whether other modules except the grid module in the renewable energy system normally operate, if the modules are detected to be faults, stopping operation or leaving the grid, and if the modules are not detected to be faults, performing the step S2;
step S2, maximum powerTracking: maximum output power P to photovoltaic module Light (es) Maximum output power P of wind energy module Wind power Tracking if the maximum output power P of the photovoltaic module is judged Light (es) And the maximum output power P of the wind energy module Wind power Total power P of the sum General (1) Whether or not it is greater than the load power P Negative pole If P is General (1) ≤P Negative pole Then go to step S3, if P General assembly ＞P Negative pole And then to load power supply, start electrolysis trough module hydrogen manufacturing simultaneously to lithium battery pack module equalizing charge, according to the operating condition of the height control electrolysis trough module of charges of electricity and hydrogen use cost and lithium battery pack module: when the electricity charge is higher than the hydrogen gas use charge, the electrolytic cell module is in a low-power output state, and the lithium battery pack module is in a low-power charging state; when the electricity charge is lower than the hydrogen use charge, the electrolytic bath module is in a maximum power output state, the lithium battery pack module is in a high-power charging state until the hydrogen storage tank and the lithium battery pack module are judged to be full, and the residual power is sold at the moment;
s3, judging the running state of the power grid module: detecting the sampling signal of the power grid module collected in the S1, judging whether the power grid module operates normally, if not, starting a lithium battery pack to discharge in a balanced manner, and supplying power to a load together with the photovoltaic module and the wind power module; if yes, accessing a power grid or starting a fuel cell module, supplying power to a load together with the photovoltaic module and the wind power module, and performing step S4;
the working states of the fuel cell module and the lithium battery pack module are controlled according to the electric charge and the hydrogen use cost in the process: when the electricity fee is higher than the hydrogen gas use fee, the fuel cell module is in a maximum power output state, and the lithium battery pack module is in a low-power charging state; when the electricity charge is lower than the hydrogen gas use charge, the fuel cell module is in a low-power output state, and the lithium battery pack module is in a high-power charging state;
s4, calculating the yield of hydrogen production by electrolyzing water by using peak valley
Judging whether the power consumption peak valley is present at the moment, and if not, continuing to judge after unit time t; if the judgment result is yes, the yield of hydrogen production by water electrolysis in the peak valley is calculated, and the yield calculation formula is as follows: the yield = value of produced hydrogen energy-hydrogen energy conversion cost; judging the calculation result, starting the electrolytic cell module to produce hydrogen when the peak-valley income is larger than the electricity expense until the hydrogen storage tank is judged to be full, and controlling the working state of the electrolytic cell module during operation according to the height of the electricity expense and the hydrogen use expense: when the electricity charge is higher than the hydrogen gas use charge, the electrolytic cell module is in a low-power output state; when the electricity fee is lower than the hydrogen gas use fee, the electrolytic cell module is in a maximum power output state; and if the peak-valley electrolysis yield is not greater than the electricity fee, not starting the electrolytic cell module.
The invention designs a minimum value triggering and dynamic programming combined algorithm aiming at the problem of charge-discharge balance of the lithium battery pack, combines minimum value triggering control with the innovativeness of the dynamic programming algorithm, and adopts minimum value triggering in the charging process; and a dynamic programming algorithm is adopted in the discharging process, the optimal battery pack configuration is solved, the discharge capacity of the battery pack is maximized, the redundant batteries are fully utilized, the battery packs are balanced quickly and in a small number of switching actions under the condition that the battery packs are inconsistent, and the maximum discharge capacity of the battery packs is realized.
As shown in fig. 4, the step of equalizing charge of the lithium battery pack module in step S2 is:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, the SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is sequenced from large to small, and charging is started from the first lithium battery cluster;
step b, judging whether the SOC of the 2 nd battery cell in the lithium battery cluster is equal to the minimum SOC of the SOCs of the N battery cells in the lithium battery cluster min If yes, accessing 3 rd to Nth batteries for charging, and if not, returning to the previous step of circulation;
step c, judging whether the SOC of all the N batteries is 1 so as to judge whether the batteries are fully charged, if not, returning to the step a to continue balancing, if so, proving that the charging balancing is finished, and cutting off the lithium battery clusters which are charged;
and d, repeating the step b and the step c, and charging the next lithium battery cluster until all the lithium battery clusters in the lithium battery pack module are charged.
The step S3 of the lithium battery pack module for balanced discharge comprises the following steps:
step A, detecting the SOC of each battery monomer in the lithium battery pack module, and judging that a single battery or a plurality of battery monomers in the lithium battery pack module are in an inconsistent state when the difference between the SOC of each battery monomer and a standard value is more than 0.005;
and step B, reconstructing according to the maximum SOC output in the lithium battery pack module through a dynamic programming algorithm, so that the charge states of all the single batteries can tend to be consistent in the discharging process, and all the single batteries in the lithium battery pack module complete the discharging process at the same time. The dynamic programming algorithm in the step B comprises the following specific steps:
b-1, designing a data structure required by a dynamic programming algorithm: array v [ n ]]Storing the SOC of n batteries, wherein the number of the batteries connected into operation every time is W, and the array C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery is accessed to operate or not;
step B-2, initialization: array C [n+1][W+1] All 0 th row and 0 th column of (1) are set to 0;
step B-3, circulation stage: determining the optimal value obtained under the condition that the previous i batteries can be accessed to operate according to the following formula;
taking n batteries and 1 battery cluster for discharging as an example, for a single battery i, the SOC is v i ；
For any one cell x i Is "x i =1 or x i =0", i =1,2, \8230, n, for x i-1 After decision, sequence (x) 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i The problem is in one of two states:
(5) When the battery accessed by the battery cluster reaches the upper limit and the battery i is not allowed to be accessed continuously, x i =0, SOC of battery cluster is not increased;
(6) The battery cluster can be accessed to a battery i, then x i =1, increase in SOC of Battery Clusterv i ；
In the above two cases, the maximum value of the SOC of the battery cluster is x i Value after decision making;
let C [i][j] Representing sub-problems
Of optimum value, i.e.
Then
Sub-problem indicating equalized charging or discharging of battery pack
If i =0 or j =0, let C [0][j] ＝C [i][0] I ≦ n ≦ 0,1 ≦ j ≦ W, if j<w i The ith battery must not be accessed, i.e. x i If not =0, then
If the ith battery is switched on for operation, i.e. x i =1, then
Whereby when j ≧ w i When, C [i][j] Taking the maximum of the two, i.e.
The recursive definition of the optimum value thus obtained is as follows:
C [0][j] ＝C [i][0] ＝0
when i =1, calculate C [1][j] ，1≤j≤W；
When i =2, calculate C [2][j] ，1≤j≤W；
……
When i = n, calculate C [n][W] At this time, C [n][W] Is an optimal value;
b-4, positioning the batteries, determining the access state of each battery, and determining the access state of each battery according to the battery position C [n][W] Is pushed forward, if C [n][W] >C [n-1][W] If yes, then indicating the nth battery access operation, x n =1; otherwise, the nth battery is not accessed, x n If =0, the first n-1 batteries are accessed into the battery cluster with the number of the batteries W, and so on until it is determined whether the 1 st battery is accessed for operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] X, which indicates that the ith battery is not in access operation i ＝0；
If C [i][j] >C [i-1][j] (ii) description of ith battery access operation, x i ＝1。
As shown in fig. 3, the energy management method and process of the energy storage module of the present invention are schematically illustrated. The specific energy management method of the energy storage module comprises the following steps: the electrolytic cell, the fuel cell working state and the lithium battery pack charging power control method comprise the following steps: the basis of the control of the working state of the electrolytic cell, the fuel cell and the charging power of the lithium battery pack is the charge of electricity and the charge of hydrogen. When the electricity charge is high and the use cost of hydrogen is low, the electrolytic cell is in a lower power output state, the fuel cell is in a maximum power output state, and the lithium battery pack is in a low-power charging state; when the electricity charge is low and the hydrogen use cost is high, the electrolytic cell is in a maximum power output state, the fuel cell is in a lower power output state, and the lithium battery pack is in a high-power charging state; the electrolytic cell and the fuel cell heat generation distribution method comprise the following steps: the heat distribution of the electrolytic cell and the fuel cell is based on the electricity cost and the hydrogen use cost. When the electricity cost is high and the hydrogen use cost is low, more heat is planned to be provided for the fuel cell, and the optimal working temperature is achieved through heat management; when the electricity cost is low and the hydrogen use cost is high, more heat is planned to be provided for the electrolytic cell, and the electrolytic cell is enabled to reach the optimal working temperature through heat management.
Claims (6)
1. A method of energy management for a renewable energy system, comprising: the method comprises the following steps:
s1, detecting sampling signals of each module of the renewable energy system: the renewable energy system comprises a photovoltaic module, a wind energy module, a power grid module, a fuel cell module, an electrolytic cell module, a lithium battery pack module and a hydrogen storage tank, and is used for judging whether other modules except the power grid module in the renewable energy system normally operate or not, stopping operation or leaving the power grid if the modules except the power grid module in the renewable energy system are detected to be in fault, and performing the step S2 if the modules are not in fault;
step S2, maximum power tracking: maximum output power P to photovoltaic module Light (es) Maximum output power P of wind energy module Wind power Tracking if the maximum output power P of the photovoltaic module is judged Light (es) And the maximum output power P of the wind energy module Wind power Total power P of the sum General assembly Whether or not it is greater than the load power P Negative pole If P is General assembly ≤P Negative pole Then go to step S3, if P is General (1) ＞P Negative pole Supplying power to the load, starting the electrolytic cell module to produce hydrogen, and uniformly charging the lithium battery pack module until the hydrogen storage tank and the lithium battery pack module are full, and selling the residual power;
s3, judging the running state of the power grid module: detecting the sampling signal of the power grid module collected in the S1, judging whether the power grid module operates normally, if not, starting a lithium battery pack to discharge in a balanced manner, and supplying power to a load together with the photovoltaic module and the wind power module; if the judgment result is yes, the power grid is connected or the fuel cell module is started, the photovoltaic module and the wind power module are used for supplying power to a load, and the step S4 is carried out;
s4, calculating the yield of hydrogen production by water electrolysis by using peak valley: judging whether the power consumption peak valley is in the current time, if not, continuing to judge after unit time t; if the judgment result is yes, the yield of hydrogen production by water electrolysis in the peak valley is calculated, and the yield calculation formula is as follows: the yield = value of produced hydrogen energy-hydrogen energy conversion cost; judging the calculation result, and starting the electrolytic cell module to produce hydrogen when the peak-valley yield is greater than the electricity consumption until the hydrogen storage tank is judged to be full; and if the peak-to-valley electrolysis yield is not greater than the electricity fee, not starting the electrolytic cell module.
2. The method for energy management of renewable energy system of claim 1, wherein: the step S2 of equalizing charge of the lithium battery pack module comprises the following steps:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, the SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is sequenced from large to small, and charging is started from the first lithium battery cluster;
step b, judging whether the SOC of the 2 nd battery cell in the lithium battery cluster is equal to the minimum SOC of the SOCs of the N battery cells in the lithium battery cluster min If yes, accessing 3 rd to Nth batteries for charging, and if not, returning to the previous step of circulation;
step c, judging whether the SOC of all the N batteries is 1 so as to judge whether the batteries are fully charged, if not, returning to the step a to continue balancing, if so, proving that the charging balancing is finished, and cutting off the lithium battery clusters which are charged;
and d, repeating the step b and the step c, and charging the next lithium battery cluster until all the lithium battery clusters in the lithium battery pack module are charged.
3. The method of energy management of a renewable energy system of claim 1, wherein: the step S3 of the equalizing discharge of the lithium battery pack module comprises the following steps:
step A, detecting the SOC of each battery monomer in the lithium battery pack module, and judging that a single battery or a plurality of battery monomers in the lithium battery pack module are in an inconsistent state when the difference between the SOC of each battery monomer and a standard value is more than 0.005;
and step B, reconstructing according to the maximum SOC output in the lithium battery pack module through a dynamic programming algorithm, so that the charge states of all the single batteries can tend to be consistent in the discharging process, and all the single batteries in the lithium battery pack module complete the discharging process at the same time.
4. A method for energy management of a renewable energy system according to claim 3, wherein: the dynamic programming algorithm in the step B comprises the following specific steps:
b-1, designing a data structure required by a dynamic programming algorithm: array v [ n ]]Storing SOC of n batteries, wherein the number of the batteries in each access operation is W, and the array C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery is accessed to operate or not;
step B-2, initialization: array C [n+1][W+1] Row 0 and column 0 of (1) are all set to 0;
step B-3, circulation stage: determining the optimal value obtained under the condition that the previous i batteries can be accessed to operate according to the following formula;
taking n batteries and 1 battery cluster for discharging as an example, for a single battery i, the SOC is v i ；
For any one cell x i Is "x" as a decision i =1 or x i =0", i =1,2, \ 8230;, n, for x i-1 After decision, sequence (x) 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i The problem is in one of two states:
(1) When the battery accessed by the battery cluster reaches the upper limit and the battery i is not allowed to be accessed continuously, x i =0, SOC of battery cluster is not increased;
(2) The battery cluster can be accessed to a battery i, then x i =1 SOC increase of battery cluster v i ；
In the above two cases, the maximum value of the SOC of the battery cluster is x i Value after decision making;
let C [i][j] Representing subproblems
An optimum value of (2), i.e.
Then
Indicating a sub-problem of equalizing charge or discharge of a battery
If i =0 or j =0, let C [0][j] ＝C [i][0] I ≦ n ≦ 0,1 ≦ j ≦ W, if j<w i The ith battery must not be accessed, i.e. x i If not =0, then
If the ith battery is switched on for operation, i.e. x i =1, then
Whereby when j ≧ w i When, C [i][j] Taking the maximum of the two, i.e.
The recursive definition of the optimum value that can be obtained from this is as follows:
C [0][j] ＝C [i][0] ＝0
when i =1, calculate C [1][j] ，1≤j≤W；
When i =2, calculate C [2][j] ，1≤j≤W；
……
When i = n, calculate C [n][W] At this time, C [n][W] Is an optimal value;
b-4, positioning the batteries, determining the access state of each battery, and determining the access state of each battery according to the battery position C [n][W] Is pushed forward, if C [n][W] >C [n-1][W] Then it indicates the nth battery access operation, x n =1; otherwiseThe nth battery is not accessed, x n If =0, the first n-1 batteries are accessed into the battery cluster with the number of the batteries W, and so on until it is determined whether the 1 st battery is accessed for operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] When the ith battery is not accessed to operate, x i ＝0；
If C [i][j] >C [i-1][j] (ii) description of ith battery access operation, x i ＝1。
5. The method of energy management of a renewable energy system of claim 1, wherein: when the electrolytic cell module or the fuel cell module or the lithium battery pack module is judged to be in the running state in the steps S2, S3 and S4, controlling the working state of the electrolytic cell module, the fuel cell module and the lithium battery pack module in running according to the electricity charge and the hydrogen use charge: when the electricity fee is higher than the hydrogen gas use fee, the electrolytic cell module is in a low-power output state, the fuel cell module is in a maximum power output state, and the lithium battery pack module is in a low-power charging state; when the electricity charge is lower than the hydrogen gas use charge, the electrolytic cell module is in a maximum power output state, the fuel cell module is in a low power output state, and the lithium battery pack module is in a high power charging state.
6. The method for energy management of renewable energy system of claim 5, wherein: when the electrolytic cell module or the fuel cell module is judged to be in the operation state in the steps S2, S3 and S4, controlling the heat management when the electrolytic cell module and the fuel cell module operate according to the electricity cost and the hydrogen use cost: providing heat for the fuel cell module to reach the optimal working temperature when the electricity cost is higher than the hydrogen gas use cost; when the electricity fee is lower than the hydrogen gas use fee, heat is provided for the electrolytic cell to reach the optimal working temperature.
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