CN115411770B - Energy management method of renewable energy system - Google Patents

Energy management method of renewable energy system Download PDF

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CN115411770B
CN115411770B CN202211021796.XA CN202211021796A CN115411770B CN 115411770 B CN115411770 B CN 115411770B CN 202211021796 A CN202211021796 A CN 202211021796A CN 115411770 B CN115411770 B CN 115411770B
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battery
power
lithium battery
charge
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CN115411770A (en
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章仕起
郭小强
孔寒冰
宋晓飞
张哲�
弗雷德·布拉比格
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Yanshan University
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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
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • 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
    • 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
    • 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
    • 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
    • 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
    • H02J7/0025—Sequential battery discharge in systems with a plurality of batteries
    • 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
    • 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]
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • 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
    • H02J2300/28—The renewable source being wind energy
    • 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
    • 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)
  • Chemical & Material Sciences (AREA)
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  • Materials Engineering (AREA)
  • Metallurgy (AREA)
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Abstract

The invention discloses an energy management method of a renewable energy system, which comprises the following steps: step S1, detecting sampling signals of all modules of a renewable energy system, and judging whether other 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 or not according to the relation between the total power of the photovoltaic module and the wind energy module and the load power, and carrying out balanced charging on the lithium battery pack module; step S3, judging the running condition of the power grid module: determining a load power supply mode according to the running condition; and S4, carrying out income calculation of hydrogen production by water electrolysis by using the peak valley, and determining whether to start the electrolytic tank. The invention can realize the maximum economic benefit operation of the system on the basis of ensuring the long-term stable operation of the system, and the reasonable scheduling of the steady-state operation and the fault operation of the renewable energy system or the micro-grid containing hydrogen storage.

Description

Energy management method of renewable energy system
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, social and population growth, the global energy demand is increasing. Non-renewable energy sources such as coal, petroleum and natural gas occupy important roles in energy consumption structures in the world, so that reserves of the non-renewable energy sources are greatly reduced, and 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 aggravated, so that the life of people is influenced. With the increasing demand for electricity, large power grids are rapidly evolving with the strong advantages they represent. However, the operation cost and difficulty of the traditional large power grid are increasing, and the defects of the traditional large power grid are also increasing. At present, the distributed power generation technology is greatly developed, and the full utilization of renewable energy sources becomes a main way for solving the problem of future energy sources. The China goes out of the project of the medium-long term development of renewable energy sources, provides guarantee and policy support for the related technology of distributed power generation represented by photovoltaic power generation and wind power generation from the aspect of legislation, and improves the utilization of renewable energy sources to a strategic height. The distributed power generation technology can fully utilize energy resources of various places, and is flexible, economical and environment-friendly. But on the other hand, a large number of distributed power sources dispersed is not controllable for large power grids. After the capacity permeability of the distributed power supply reaches high, reliable operation of the power distribution system is realized, and the power quality of users is ensured, which is also a greater challenge.
In order to alleviate the contradiction between distributed power sources and traditional large grids, micro-grid technology has received more attention. The micro-grid is a single controllable unit which consists of a plurality of 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, is connected with a large power grid through a contact point, and when the power quality of the power grid does not meet the requirement or fails, the PCC point 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 hub of the distributed power supply and the power distribution network, so that adverse effects on the power supply reliability and the power quality caused by the micro-grid are reduced, renewable energy sources can be fully utilized, and the energy utilization rate is improved.
Under the background of the great initiative of China for developing green energy, the energy Internet is widely focused, and wind power and photovoltaic power generation serve as main forms of new energy power generation, so that the energy Internet becomes a research hotspot. However, because the output power is fluctuated due to the intermittence and fluctuation of the device, the micro-grid power supply is affected, the output power quality of the system is affected, and the key of solving the problem is cooperation with an energy storage system. The generation, storage and conversion of hydrogen energy are important links of energy Internet, the hydrogen energy storage is focused on the advantages of cleanness, high efficiency, high energy density and the like, and the research of taking an electrolytic tank-hydrogen storage tank-fuel cell circulating system as an energy storage unit has engineering practice guiding value.
At present, the energy system of the renewable energy system has the following defects: the energy distribution is unreasonable, so that the system reliability is poor; the system module has weak comprehensiveness, low economy and energy waste.
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 or fault operation of the renewable energy system or micro-grid containing hydrogen storage.
In order to solve the technical problems, the invention adopts the following technical scheme: an energy management method of a renewable energy system, comprising the steps of:
step 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 tank module, a lithium battery pack module and a hydrogen storage tank, whether other modules except the power grid module in the renewable energy system normally operate or not is judged, if the renewable energy system is detected to be faulty, the operation is stopped or the power grid is disconnected, and if the renewable energy system is not faulty, the step S2 is carried out;
step S2, maximum power tracking: maximum output power P of photovoltaic module Light source Maximum output power P of wind energy module Wind power Tracking, if the maximum output power P of the photovoltaic module is judged Light source And maximum output power P of wind energy module Wind power Total power of sum P Total (S) Whether or not to be greater than the load power P Negative pole If P Total (S) ≤P Negative pole Step S3 is performed, if P Total (S) ＞P Negative pole Supplying power to the load, starting the electrolytic tank module to produce hydrogen, and equalizing charge on the lithium battery module until the hydrogen storage tank and the lithium battery module are judged to be full, and then, leavingSelling residual power;
step S3, judging the running condition of the power grid module: detecting the sampling signal of the power grid module acquired in the step S1, judging whether the power grid module operates normally, and if not, starting the lithium battery pack to discharge in an equalizing mode, 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 a photovoltaic module and a wind power module, and performing step S4;
s4, carrying out income calculation of hydrogen production by water electrolysis by using the peak valley: judging whether the current is in the peak valley or not, if not, continuing to judge after the unit time t; if yes, calculating the income of hydrogen production by water electrolysis in the peak valley, wherein the income calculation formula is as follows: revenue = value of hydrogen energy produced-cost of hydrogen energy conversion; judging the calculation result, and starting the electrolytic tank module to produce hydrogen when the peak-valley income is greater than the electricity fee until the hydrogen storage tank is judged to be full; if the peak Gu Dianjie benefit is not greater than the electricity rate, then the electrolyser module is not started.
The technical scheme of the invention is further improved as follows: the step of equalizing charge of the lithium battery module in the step S2 is as follows:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, and the battery charge state SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is ordered from big 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 value SOC of the SOC in the N battery cells of the lithium battery cluster min If yes, accessing the 3 rd to N th batteries for charging, and if not, returning to the previous cycle;
step c, judging whether the SOC of all N batteries is 1 so as to judge whether the batteries are full, if not, returning to the step a to continue balancing, if so, proving that the charge balancing is finished, and cutting off the lithium battery clusters which are already 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 module equalization discharge in the step S3 is as follows:
step A, detecting the battery charge state SOC of each battery cell in the lithium battery pack module, and judging that one or more battery cells in the lithium battery pack module are in an inconsistent state when the difference between the battery charge state SOC of each battery cell and a standard value is greater than 0.005;
and 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 tend to be consistent in discharging, and discharging all the single batteries in the lithium battery pack module simultaneously.
The technical scheme of the invention is further improved as follows: the specific steps of the dynamic programming algorithm in the step B are as follows:
step 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 which are accessed to run each time is W, and the number is set C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery is connected to operate;
step B-2, initializing: array C [n+1][W+1] 0 th row and 0 th column of (a) are all set to 0;
step B-3, a circulation stage: determining an optimal value obtained under the condition that the first i batteries can be connected into operation according to the following formula;
taking n batteries and 1 battery cluster discharge as an example, for the battery cell i, the state of charge SOC is v i ；
For any one cell x i Is determined as' x i =1 or x i =0 ", i=1, 2, …, n for x i-1 After decision making, the sequence (x 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i When the problem is in one of two states:
(3) If the battery cluster is accessed by the battery which reaches the upper limit and is not allowed to be accessed continuously, x is the number i =0, the SOC of the battery cluster does not increase;
(4) The battery cluster may be connected to a battery i,then x i =1, SOC increase v of battery cluster i ；
In both cases, the maximum value of the battery cluster SOC is x i The value after decision making;
let C [i][j] Representing sub-questions
Figure BDA0003814287740000041
Is the optimum value of->
Figure BDA0003814287740000042
Then
Figure BDA0003814287740000043
Sub-problem representing balanced charge or discharge of battery pack +.>
Figure BDA0003814287740000044
If i=0 or j=0, let C [0][j] ＝C [i][0] =0, 1.ltoreq.i.ltoreq.n, 1.ltoreq.j.ltoreq.W, if j<w i The ith cell must not be accessed, i.e. x i =0, then->
Figure BDA0003814287740000051
If the ith battery is in operation, i.e. x i =1, then
Figure BDA0003814287740000052
Thus when j is greater than or equal to w i At time C [i][j] Taking the maximum value of the two, namely
Figure BDA0003814287740000053
The recursive definition of the optimum thus obtained is as follows:
C [0][j] ＝C [i][0] ＝0
Figure BDA0003814287740000054
when i=1, C is obtained [1][j] ，1≤j≤W；
When i=2, C is obtained [2][j] ，1≤j≤W；
……
When i=n, C is obtained [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 according to C [n][W] The value of (1) is pushed forward if C [n][W] >C [n-1][W] Indicating that the nth battery is in operation, x n =1; otherwise, the nth battery is not accessed, x n =0, then the previous n-1 batteries are connected into a battery cluster with the number of W, and so on until it is determined whether the 1 st battery is connected into operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] Indicating that the ith battery is not in operation, x i ＝0；
If C [i][j] >C [i-1][j] Description of i-th battery access operation, x i ＝1。
The technical scheme of the invention is further improved as follows: when the electrolytic cell module, the fuel cell module or the lithium battery module in the steps S2, S3 and S4 are judged to be in the operation state, the operation states of the electrolytic cell module, the fuel cell module and the lithium battery module are controlled according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, the electrolytic tank 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 use charge, the electrolyzer module is in a maximum power output state, the fuel cell module is in a lower power output state, and the lithium battery module is in a high power charge state.
The technical scheme of the invention is further improved as follows: when the electrolyzer module or the fuel cell module is judged to be in the operation state in the steps S2, S3 and S4, controlling the electrolyzer module and the heat management when the fuel cell module is operated according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, providing heat for the fuel cell module to reach the optimal working temperature; when the electricity charge is lower than the hydrogen use charge, heat is provided for the electrolyzer to reach the optimal working temperature.
By adopting the technical scheme, the invention has the following technical progress:
1. the invention designs an energy management method suitable for a renewable energy system or a micro-grid, which can realize the maximum economic benefit operation of the system and the reasonable scheduling of the steady operation and the fault operation of the renewable energy system or the micro-grid containing hydrogen energy storage on the basis of ensuring the long-term stable operation of the system. 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 method comprises the energy management of an electrolytic tank, a fuel cell and a hydrogen storage tank, and has wider applicability;
2. the invention designs a minimum value triggering and dynamic programming combined algorithm aiming at the charge and discharge balance problem of the lithium battery pack, creatively combines the minimum value triggering control and the dynamic programming algorithm, and adopts the 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 maximum discharge capacity of the battery pack is realized, the redundant battery is fully utilized, the battery pack is balanced rapidly with few switching actions under the condition of inconsistent battery packs, and the maximum discharge capacity of the battery pack is realized.
Drawings
FIG. 1 is a schematic diagram of the structure of the renewable energy system of the present invention;
FIG. 2 is a schematic illustration of an energy management method of the renewable energy system of the present invention;
fig. 3 is a schematic process diagram of an energy storage module energy management method of the present invention.
Fig. 4 is a schematic view of a battery pack structure
Detailed Description
The invention is further illustrated by the following examples:
as shown in fig. 1, the renewable energy system comprises a photovoltaic module, a wind energy module, a power grid module, a fuel cell module, an electrolytic tank module, a lithium battery pack module and a hydrogen storage tank, wherein electric energy generated by the photovoltaic module and the wind energy module is used for supplying power to a load, when the total power generated by the photovoltaic module and the wind energy module is remained, a part of electric energy is converted into hydrogen energy through the electrolytic tank and stored in the hydrogen storage tank, and the other part of electric energy is stored in the lithium battery pack module, and if the residual electric energy is remained, the electric energy is sold; the power grid module is connected with power supply when the photovoltaic module and the wind energy module cannot meet the requirement of load power supply, and can determine whether to start the electrolytic tank module to convert 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 a load.
As shown in fig. 2, the energy management method of the renewable energy system of the present invention comprises the following specific steps:
step S1, detecting sampling signals of each module of the renewable energy system: judging whether other modules except the power grid module in the renewable energy system normally operate or not, if the modules are detected to be faulty, stopping operation or off-grid, and if the modules are not faulty, performing step S2;
step S2, maximum power tracking: maximum output power P of photovoltaic module Light source Maximum output power P of wind energy module Wind power Tracking, if the maximum output power P of the photovoltaic module is judged Light source And maximum output power P of wind energy module Wind power Total power of sum P Total (S) Whether or not to be greater than the load power P Negative pole If P Total (S) ≤P Negative pole Step S3 is performed, if P Total (S) ＞P Negative pole And supplying power to the load, starting the electrolytic cell module to produce hydrogen, and uniformly charging the lithium battery module, wherein the working states of the electrolytic cell module and the lithium battery module are controlled according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, the electrolytic tank 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 tank module is in a maximum power output state, and 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;
step S3, judging the running condition of the power grid module: detecting the sampling signal of the power grid module acquired in the step S1, judging whether the power grid module operates normally, and if not, starting the lithium battery pack to discharge in an equalizing mode, 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 a photovoltaic module and a wind power module, and performing step S4;
in the process, the working state of the fuel cell module and the lithium battery pack module is controlled according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, 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 use charge, the fuel cell module is in a low power output state, and the lithium battery pack module is in a high power charge state;
s4, carrying out income calculation of hydrogen production by water electrolysis by using peak valley
Judging whether the current is in the peak valley or not, if not, continuing to judge after the unit time t; if yes, calculating the income of hydrogen production by water electrolysis in the peak valley, wherein the income calculation formula is as follows: revenue = value of hydrogen energy produced-cost of hydrogen energy conversion; judging the calculation result, when the peak-valley income is greater than the electricity charge, starting the electrolytic tank module to produce hydrogen until the hydrogen storage tank is judged to be full, and controlling the working state of the electrolytic tank module when in operation according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, the electrolytic tank module is in a low power output state; when the electricity charge is lower than the hydrogen use charge, the electrolyzer module is in a maximum power output state; if the peak Gu Dianjie benefit is not greater than the electricity rate, then the electrolyser module is not started.
The invention designs a minimum value triggering and dynamic programming combined algorithm aiming at the charge and discharge balance problem of the lithium battery pack, creatively combines the minimum value triggering control and the dynamic programming algorithm, and adopts the 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 maximum discharge capacity of the battery pack is realized, the redundant battery is fully utilized, the battery pack is balanced rapidly with few switching actions under the condition of inconsistent battery packs, and the maximum discharge capacity of the battery pack is realized.
As shown in fig. 4, the step of equalizing charge of the lithium battery module in step S2 is as follows:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, and the battery charge state SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is ordered from big 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 value SOC of the SOC in the N battery cells of the lithium battery cluster min If yes, accessing the 3 rd to N th batteries for charging, and if not, returning to the previous cycle;
step c, judging whether the SOC of all N batteries is 1 so as to judge whether the batteries are full, if not, returning to the step a to continue balancing, if so, proving that the charge balancing is finished, and cutting off the lithium battery clusters which are already 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 of the lithium battery module equalization discharge in the step S3 is as follows:
step A, detecting the battery charge state SOC of each battery cell in the lithium battery pack module, and judging that one or more battery cells in the lithium battery pack module are in an inconsistent state when the difference between the battery charge state SOC of each battery cell and a standard value is greater than 0.005;
and 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 tend to be consistent in discharging, and discharging all the single batteries in the lithium battery pack module simultaneously. The specific steps of the dynamic programming algorithm in the step B are as follows:
step 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 which are accessed to run each time is W, and the number is set C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery is connected to operationA row;
step B-2, initializing: array C [n+1][W+1] 0 th row and 0 th column of (a) are all set to 0;
step B-3, a circulation stage: determining an optimal value obtained under the condition that the first i batteries can be connected into operation according to the following formula;
taking n batteries and 1 battery cluster discharge as an example, for the battery cell i, the state of charge SOC is v i ；
For any one cell x i Is determined as' x i =1 or x i =0 ", i=1, 2, …, n for x i-1 After decision making, the sequence (x 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i When the problem is in one of two states:
(5) If the battery cluster is accessed by the battery which reaches the upper limit and is not allowed to be accessed continuously, x is the number i =0, the SOC of the battery cluster does not increase;
(6) The battery cluster can be accessed into the battery i, then x i =1, SOC increase v of battery cluster i ；
In both cases, the maximum value of the battery cluster SOC is x i The value after decision making;
let C [i][j] Representing sub-questions
Figure BDA0003814287740000091
Is the optimum value of->
Figure BDA0003814287740000092
Then
Figure BDA0003814287740000101
Sub-problem representing balanced charge or discharge of battery pack +.>
Figure BDA0003814287740000102
If i=0 or j=0, let C [0][j] ＝C [i][0] =0, 1.ltoreq.i.ltoreq.n, 1.ltoreq.j.ltoreq.W, if j<w i The ith cell must not be accessed, i.e. x i =0, then->
Figure BDA0003814287740000103
If the ith battery is in operation, i.e. x i =1, then
Figure BDA0003814287740000104
Thus when j is greater than or equal to w i At time C [i][j] Taking the maximum value of the two, namely
Figure BDA0003814287740000105
The recursive definition of the optimum thus obtained is as follows:
C [0][j] ＝C [i][0] ＝0
Figure BDA0003814287740000106
when i=1, C is obtained [1][j] ，1≤j≤W；
When i=2, C is obtained [2][j] ，1≤j≤W；
……
When i=n, C is obtained [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 according to C [n][W] The value of (1) is pushed forward if C [n][W] >C [n-1][W] Indicating that the nth battery is in operation, x n =1; otherwise, the nth battery is not accessed, x n =0, then the previous n-1 batteries are connected into a battery cluster with the number of W, and so on until it is determined whether the 1 st battery is connected into operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] Indicating that the ith battery is not in operation, x i ＝0；
If C [i][j] >C [i-1][j] Description of i-th battery access operation, x i ＝1。
As shown in fig. 3, the energy storage module energy management method of the present invention is a schematic process diagram. The specific energy storage module energy management method comprises the following steps: the method for controlling the charging power of the electrolytic tank, the fuel cell working state and the lithium battery pack comprises the following steps: the basis of the working states of the electrolytic tank and the fuel cell and the charging power control of the lithium battery pack is the electricity charge and the hydrogen use charge. When the electricity charge is high and the hydrogen use charge is low, the electrolytic tank 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 charge is high, the electrolytic tank 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; an electrolytic cell and a fuel cell heat generation distribution method: the heat distribution of the electrolytic tank and the fuel cell is based on the electricity charge and the hydrogen use charge. When the electricity charge is high and the hydrogen use charge is low, planning to provide more heat for the fuel cell, and enabling the fuel cell to reach the optimal working temperature through heat management; when the electricity charge is low and the hydrogen use charge is high, the electrolysis cell is planned to provide more heat, and the optimal working temperature is achieved through heat management.

Claims (3)

1. An energy management method for a renewable energy system, characterized by: the method comprises the following steps:
step 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 tank module, a lithium battery pack module and a hydrogen storage tank, whether other modules except the power grid module in the renewable energy system normally operate or not is judged, if the renewable energy system is detected to be faulty, the operation is stopped or the power grid is disconnected, and if the renewable energy system is not faulty, the step S2 is carried out;
step S2, maximum power tracking: maximum output power P of photovoltaic module Light source Maximum output power P of wind energy module Wind power Tracking and judging the maximum output power P of the photovoltaic module Light source And maximum output power P of wind energy module Wind power Total power of sum P Total (S) Whether or not to be greater than the load power P Negative pole If P Total (S) ≤P Negative pole Step S3 is performed, if P Total (S) ＞P Negative pole Supplying power to the load, starting the electrolytic tank module to produce hydrogen, and uniformly charging the lithium battery module until the hydrogen storage tank and the lithium battery module are judged to be full, and selling the residual power at the moment;
the lithium battery module equalizing charge step is:
step a, a lithium battery pack module consists of a plurality of lithium battery clusters, and the battery charge state SOC of each battery monomer in each lithium battery cluster is estimated, the SOC is ordered from big 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 value SOC of the SOC in the N battery cells of the lithium battery cluster min If not, accessing the 3 rd to the N th battery cells for charging; if yes, charging the 2 nd to the N th battery cells;
c, judging whether the SOC of all N battery monomers is 1 so as to judge whether the battery is full, if not, returning to the step a to continue balancing, if so, proving that the charge balancing is finished, and cutting off the lithium battery clusters which are already charged;
step 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;
step S3, judging the running condition of the power grid module: detecting the sampling signal of the power grid module acquired in the step S1, judging whether the power grid module operates normally, and if not, starting the lithium battery pack module to discharge in an equalizing mode, and supplying power to a load together with the photovoltaic module and the wind energy module; if yes, accessing a power grid or starting a fuel cell module, supplying power to a load together with a photovoltaic module and a wind energy module, and performing step S4;
the lithium battery module performs the following steps of:
step A, detecting the battery charge state SOC of each battery cell in the lithium battery pack module, and judging that a single or a plurality of battery cells in the lithium battery pack module are in an inconsistent state when the difference between the battery charge state SOC of each battery cell and a standard value is larger than 0.005;
and 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 battery cells tend to be consistent when discharging, and simultaneously completing discharging of all the battery cells in the lithium battery pack module, wherein the specific steps of the dynamic programming algorithm are as follows:
step B-1, designing a data structure required by a dynamic programming algorithm: array v [ n ]]Storing the SOC of n battery cells, wherein the number of the battery cells which are accessed to run each time is W, and the number is set C [n+1][W+1] Storing the execution result of each iteration; array x [ n ]]Indicating whether each battery cell is connected to operate;
step B-2, initializing: array C [n+1][W+1] 0 th row and 0 th column of (a) are all set to 0;
step B-3, a circulation stage: determining an optimal value obtained under the condition that the first i battery units can be connected to operation according to the following method;
taking n battery cells and 1 battery cluster discharge as an example, for the ith battery cell, its state of charge SOC is v i ；
The decision for the ith cell is "x i =1 or x i =0 ", i=1, 2, …, n for x i-1 After decision making, the sequence (x 1 ,x 2 ,…,x i-1 ) Has been determined, at decision x i When the problem is in one of two states:
(1) The battery cell accessed by the battery cluster reaches the upper limit, and the ith battery cell is not allowed to be accessed continuously, x is the number i =0, the SOC of the battery cluster does not increase;
(2) The battery cluster can be accessed into the ith battery cell, x is i =1, SOC increase v of battery cluster i ；
In both cases, the maximum value of the battery cluster SOC is x i The value after decision making;
let C [i][j] Representing sub-questions
Figure FDA0004174213250000021
Is the optimum value of->
Figure FDA0004174213250000022
Then
Figure FDA0004174213250000031
Sub-problem representing balanced charge or discharge of battery pack +.>
Figure FDA0004174213250000032
If i=0 or j=0, let C [0][j] ＝C [i][0] =0, 1.ltoreq.i.ltoreq.n, 1.ltoreq.j.ltoreq.W, if j<w i The ith cell must not be accessed, i.e. x i =0, then->
Figure FDA0004174213250000033
If the ith battery cell is connected to run, i.e. x i =1, then
Figure FDA0004174213250000034
Thus when j is greater than or equal to w i At time C [i][j] Taking the maximum value of the two, namely
Figure FDA0004174213250000035
The recursive definition of the optimum thus obtained is as follows:
C [0][j] ＝C [i][0] ＝0
Figure FDA0004174213250000036
when i=1, C is obtained [1][j] ，1≤j≤W；
When i=2, C is obtained [2][j] ，1≤j≤W；
……
When i=n, C is obtained [n][W] At this time, C [n][W] Is an optimal value;
b-4, positioning the battery cells, determining the access state of each battery cell, and according to C [n][W] The value of (1) is pushed forward if C [n][W] >C [n-1][W] Then indicateThe nth battery cell is connected to run, x n =1; otherwise, the nth battery cell is not accessed, x n =0, then the first n-1 cells are connected into the battery cluster with the number of the cells connected into operation being W, and so on until it is determined whether the 1 st cell is connected into operation, thereby obtaining the following relation:
if C [i][j] ＝C [i-1][j] Indicating that the ith battery cell is not connected to operate, x i ＝0；
If C [i][j] >C [i-1][j] Description of the i-th Battery cell Access run, x i ＝1；
S4, carrying out income calculation of hydrogen production by water electrolysis by using the peak valley: judging whether the current is in the peak valley or not, if not, continuing to judge after the unit time t; if yes, calculating the income of hydrogen production by water electrolysis in the peak valley, wherein the income calculation formula is as follows: revenue = value of hydrogen energy produced-cost of hydrogen energy conversion; judging the calculation result, and starting the electrolytic tank module to produce hydrogen when the income is greater than the electricity fee until the hydrogen storage tank is judged to be full; and if the income is not greater than the electricity fee, the electrolytic tank module is not started.
2. The energy management method of a renewable energy system of claim 1, wherein: when the electrolytic cell module, the fuel cell module or the lithium battery module in the steps S2, S3 and S4 are judged to be in the operation state, the operation states of the electrolytic cell module, the fuel cell module and the lithium battery module are controlled according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, the electrolytic tank 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 use charge, the electrolyzer module is in a maximum power output state, the fuel cell module is in a low power output state, and the lithium battery module is in a high power charge state.
3. The energy management method of a renewable energy system of claim 2, wherein: when the electrolyzer module or the fuel cell module is judged to be in the operation state in the steps S2, S3 and S4, controlling the electrolyzer module and the heat management when the fuel cell module is operated according to the electricity charge and the hydrogen use charge: when the electricity charge is higher than the hydrogen use charge, providing heat for the fuel cell module to reach the optimal working temperature; when the electricity charge is lower than the hydrogen use charge, heat is provided for the electrolyzer to reach the optimal working temperature.
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