CN112152258B - Energy control method and device of distributed energy system - Google Patents

Energy control method and device of distributed energy system Download PDF

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CN112152258B
CN112152258B CN202010925807.1A CN202010925807A CN112152258B CN 112152258 B CN112152258 B CN 112152258B CN 202010925807 A CN202010925807 A CN 202010925807A CN 112152258 B CN112152258 B CN 112152258B
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power generation
generation system
energy
fuel cell
output voltage
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CN112152258A (en
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樊军
王戈
王建杰
甄镔滨
刘枫
陈旺龙
肖延嗣
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Moh Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • 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
    • H02J2300/28—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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Fuel Cell (AREA)

Abstract

The invention discloses an energy control method and device of a distributed energy system, wherein the method comprises the steps of detecting the output voltage of a renewable energy power generation system in real time and comparing the output voltage with the output voltage stabilization value of a fuel cell power generation system; when the output voltage is greater than or equal to the output voltage stabilization value, controlling to be connected into a renewable energy power generation system for power generation; when the output voltage is smaller than the output voltage stabilization value, judging whether the output power of the renewable energy power generation system is within a preset load demand power range; if so, controlling the distributed energy system to be connected to a renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system; if not, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power. The invention sets the priority control strategy of the energy, realizes the cooperative control among fuel cells, photovoltaic systems, wind power systems and other energy systems, improves the energy utilization efficiency and reduces the cost.

Description

Energy control method and device of distributed energy system
Technical Field
The invention relates to the technical field of fuel cells, in particular to an energy control method and device of a distributed energy system.
Background
The distributed energy is used as a system for providing energy for users on a load side, and is mainly used for solving the problem of power outage of a public power grid caused by more natural disasters or the problem of power demand in remote areas without the power grid. The distributed power supply system commonly used at present comprises a diesel generator, a photovoltaic power station, a storage battery and the like. The diesel generator has the defects of high working noise, harmful emission and the like; the photovoltaic power station needs enough sunshine time or matches with a large-capacity storage battery for use, has higher requirement on an installation site, and is easy to cause damage to woodland and cultivated land; the storage battery has the defects of large volume, strict requirements on environmental temperature, uncertain charging and discharging conditions and the like. In view of the above shortcomings of various energy systems, a clean, environment-friendly, and efficient novel distributed energy system is attracting high attention in the industry.
The fuel cell is used as a fourth type of power generation technology after hydraulic power, thermal power and nuclear power generation, is a silent high-efficiency power generation device which directly converts chemical energy of fuel and oxidant into electric energy in an electrochemical reaction mode without combustion, is not limited by Carnot cycle, has the advantages of cleanness, no pollution, low noise, high energy density, long continuous power supply time and the like, and outputs direct current, so that the fuel cell is more suitable for being matched with a storage battery pack to form a distributed energy system to work. However, renewable clean energy such as photovoltaic energy, wind power energy and the like is added into the existing distributed energy comprehensive utilization system, but the energy has the characteristics of discontinuity, large fluctuation, disordered output voltage and the like, so that how to cooperatively control each energy has important significance for the development of a high-efficiency utilization mode of new energy to realize multi-energy complementary comprehensive utilization.
Disclosure of Invention
The invention provides an energy control method of a distributed energy system, which is used for realizing cooperative control among energy systems such as fuel cells, photovoltaic systems, wind power systems and the like by setting a priority control strategy of energy, improving the utilization efficiency of the energy and reducing the cost.
In order to solve the above technical problem, an embodiment of the present invention provides an energy control method for a distributed energy system, where the distributed energy system is composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system, and a control system, and the method includes the following steps:
detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system to generate power;
when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel power generation system;
and when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power.
In one embodiment of the invention, the output voltage of the renewable energy power generation system and the output regulated voltage value of the fuel cell power generation system are both greater than the rated value of the charging voltage of the storage battery of the energy storage system.
In one of the embodiments of the invention, the renewable energy system comprises a solar photovoltaic power generation system; when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation, specifically:
and when the output voltage of the solar photovoltaic power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a photovoltaic input relay of the solar photovoltaic power generation system so as to connect the solar photovoltaic power generation system into the renewable energy power generation system.
In one embodiment of the invention, the renewable energy system comprises a wind power generation system; when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, specifically:
and when the output voltage of the wind power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a wind energy input relay of the wind power generation system so as to connect the wind power generation system to the renewable energy power generation system.
The present invention also provides an energy control apparatus of a distributed energy system, the distributed energy system being composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system, and a control system, the energy control apparatus including a control module configured to:
detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation;
when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel power generation system;
and when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power.
In one embodiment of the invention, the output voltage of the renewable energy power generation system and the output regulated voltage value of the fuel cell power generation system are both greater than the rated value of the charging voltage of the storage battery of the energy storage system.
In one embodiment of the invention, the renewable energy system comprises a solar photovoltaic power generation system; the control module further configured to:
and when the output voltage of the solar photovoltaic power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a photovoltaic input relay of the solar photovoltaic power generation system so as to connect the solar photovoltaic power generation system into the renewable energy power generation system.
In one of the embodiments of the invention, the renewable energy system comprises a wind power generation system; the control module further configured to:
and when the output voltage of the wind power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a wind power input relay of the wind power generation system so as to connect the wind power generation system to the renewable energy power generation system.
Compared with the prior art, the embodiment of the invention has the beneficial effects that the embodiment of the invention realizes the tracking of the system to the load power by integrating the energy sources of the fuel cell power generation system, the solar photovoltaic power generation system, the wind energy power generation system and the like and monitoring the state of charge (SOC), the charging and discharging current state and the like of the storage battery in the energy storage system, further realizes the dynamic adjustment of the fuel cell power, and effectively avoids the hysteresis of the power change of the fuel cell and the large-amplitude power fluctuation in the power compensation process. Furthermore, by adopting a multi-level energy voltage threshold priority strategy, the low-cost energy such as photovoltaic and the like in the energy system is connected into a priority power supply mode, so that the cooperative control among the energy systems such as fuel cells, photovoltaic, wind power and the like is favorably realized, the energy utilization efficiency is improved, and the cost is reduced.
Drawings
Fig. 1 is a schematic structural diagram of a distributed energy system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a fuel cell power generation system;
fig. 3 is a control logic diagram of a distributed energy system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a prototype structure of a distributed energy resource system according to one embodiment of the present invention;
FIG. 5 is a graph of fuel cell output power for a distributed energy system in accordance with one embodiment of the present invention;
6 a-6 c are graphs showing fuel cell output power and battery SOC for a distributed energy system according to an embodiment of the present invention;
fig. 7 is a step diagram of an energy control method of the distributed energy system according to an embodiment of the present invention;
fig. 8 is a flowchart of an energy control method of the distributed energy system according to an embodiment of the present invention;
fig. 9 is a schematic diagram of an energy control apparatus of the distributed energy system according to an embodiment of the present invention;
fig. 10 is a graph of output power and battery SOC of an energy control device of a distributed energy system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the embodiment of the present invention, it should be noted that, as shown in fig. 1, the embodiment of the present invention provides a distributed energy system as a system for supplying energy to users on the load side. The distributed energy system at least comprises a fuel cell power generation system, a solar photovoltaic power generation system, a wind energy power generation system, an energy storage system and a control system. As shown in fig. 2, a fuel cell in a fuel cell power generation system is a power generation device that converts chemical energy between stored fuel and oxidant into electrical energy, and the released heat can be recycled by a heat exchange unit. The fuel cell adopts quiet chemical reaction to directly convert chemical energy in a hydrogen source into electric energy, has simple structure and high energy conversion efficiency, generates pure water (containing heat) and is the most ideal energy technology at present, the source of the hydrogen source is wide, and in order to avoid the storage and transportation danger of the pure hydrogen, the conventional technologies of reforming hydrogen production and the like are usually adopted to prepare hydrogen from hydrogen-containing raw materials such as methanol and the like according to the requirements and directly enter the fuel cell without an intermediate transfer link, thereby realizing safe power generation.
The control method of the distributed energy system is executed by the control system, and comprises the following steps:
monitoring the electric quantity storage parameter and the charge-discharge parameter of the energy storage system in real time;
when the electric quantity storage parameter and the charge-discharge parameter meet a preset fuel supply holding condition, controlling the fuel power generation system to hold the power generation power of the fuel cell;
when the electric quantity storage parameter and/or the charge-discharge parameter meet a preset fuel supply increasing condition, controlling the fuel power generation system to increase the power generation power of the fuel cell;
and when the electric quantity storage parameter and/or the charge-discharge parameter meet a preset fuel supply reduction condition, controlling the fuel power generation system to reduce the power generation power of the fuel cell.
In the embodiment, the working power compensation degree of the fuel cell is controlled by the control system according to the SOC and the charging and discharging current of the storage battery by monitoring the state parameters of the storage battery fed back by the energy storage unit in the energy storage system in real time during working. The control method specifically comprises the following steps:
first, the amount of change in the fuel and oxidant allowed under optimum operating conditions is set according to the selected fuel cell characteristics so that the fuel cell power is directed to increase or decrease during the power compensation process.
Secondly, the SOC of the storage battery is determined and set according to the maximum load capacity of the distributed energy system allowed by design, and the power compensation capacity of the fuel cell is required to be larger than the power of the load in the allowed deep discharge cycle, if other energy sources such as photovoltaic energy and the like are connected, the power requirement of the fuel cell can be reduced according to the actual situation, and the main control flow chart is shown in fig. 3.
And S1, controlling the fuel power generation system by preset fuel cell power generation power when the distributed energy system is started.
Due to the chemical power generation characteristic of the fuel cell, in order to realize the automatic control of each component unit in the distributed energy system, the state of charge SOC, the charging current Ic and the discharging current If of the storage battery in the energy storage unit need to be monitored in real time, the fuel supply of the fuel cell needs to be controlled in a feedback manner, the power of the fuel cell is further adjusted, and the dynamic compensation is realized.
S2, when the state of charge SOC in the electric quantity storage parameter is more than or equal to a discharge cycle lower limit value SOCmin and less than or equal to a discharge cycle upper limit value SOCmax, the discharge current If in the charge-discharge parameter is less than or equal to a discharge current fluctuation set value Ib, and the charge current Ic in the charge-discharge parameter is less than a discharge current fluctuation set value Ia, judging that the preset fuel supply holding condition is met;
and controlling the fuel power generation system to maintain the power generated by the fuel cell when the preset fuel supply maintaining condition is met.
S3, when the SOC of the electric energy storage parameter is greater than or equal to the lower limit SOCmin of the discharge cycle and less than or equal to the upper limit SOCmax of the discharge cycle, and the discharge current If of the charge-discharge parameter is greater than the discharge current fluctuation set value Ia, or the SOC of the electric energy storage parameter is less than the lower limit SOCmin of the discharge cycle, determining that the preset fuel supply increase condition is satisfied;
and controlling the fuel power generation system to increase the power generation power of the fuel cell when the preset fuel supply increase condition is satisfied.
S4, determining that the preset fuel supply reduction condition is satisfied when the SOC of the electric energy storage parameter is greater than or equal to a lower limit SOCmin of a discharge cycle and less than or equal to an upper limit SOCmax of the discharge cycle, and the charging current Ic of the charging and discharging parameter is greater than a charging current fluctuation set value Ib, or the SOC of the electric energy storage parameter is greater than the upper limit SOCmax of the discharge cycle;
and controlling the fuel power generation system to reduce the power generation power of the fuel cell when the preset fuel supply reduction condition is met.
In this embodiment, the following parameters are further set for the energy storage unit in the energy storage system:
setting according to the performance indexes of the storage battery: the optimal upper and lower limit threshold values SOCmin and SOCmax of the discharge cycle are that the rated power generation of the system is P, the rated output power of the fuel cell is P output, the time from standby (zero load state) of the fuel cell to realizing P output-P output is t, the total capacity of the storage battery is X, and the following steps are provided:
Figure BDA0002667701360000071
Figure BDA0002667701360000072
in the formula, PiRepresents a fuel cell power generation sample power, where P1At rated power, PnZero load standby power; t is tiRepresenting the sample power duration, wherein the smaller the value, the more accurate the obtained SOC threshold value is; n represents the sample size; therefore, the type selection of the energy storage battery of the fuel cell power generation system and the setting of the SOC threshold value are determined.
In addition, for a fuel cell system capable of stably operating, the process of the rising power and the falling power of the fuel cell system with time can be regarded as a linear relation, so that the parameter setting can be effectively simplified, and the following steps are provided:
Figure BDA0002667701360000073
the battery capacity threshold control strategy is as follows:
when the distributed energy system works, the control unit monitors the SOC data of the storage battery fed back by the energy storage unit in real time, and controls whether to increase or decrease the fuel supply of the fuel cell according to the set upper limit value SOCmax and lower limit value SOCmin of the storage battery SOC, so that the output power of the fuel cell is further increased or decreased. The control strategy is as follows:
Figure BDA0002667701360000074
the strategy for controlling the charging and discharging current of the storage battery is as follows:
due to the hysteresis of the response of the fuel cell, the charging and discharging current of the storage battery is monitored in real time through the control unit, and the allowable current fluctuation value I is set, so that when the charging current Ic or the discharging current If is in the allowable fluctuation range, the fuel supply is kept, namely the output power of the fuel cell is unchanged, and when the charging and discharging current exceeds the design allowable fluctuation value, the predictive adjustment of the power of the fuel cell is actively carried out, wherein the control strategy is as follows:
Figure BDA0002667701360000081
tests and analyses were performed based on the above embodiment:
a set of 4kW distributed energy system test prototype is developed. The rated output power of the fuel cell is 4kW, the output voltage is set to 54V through a voltage-stabilizing isolation power supply, the energy storage unit is a 48V100Ah standard lithium battery module with BMS management and communication, the maximum output power is 5kW, the SOCmin is set to be 70%, the SOCmax is set to be 85%, and the allowable charging and discharging current fluctuation value I is set to be 3A.
Battery SOC threshold test
A test platform is built by using a 6kW direct current electronic load according to the system structure shown in FIG. 4, the SOC of the storage battery is adjusted to 60%, an external load is not started, the developed distributed energy system is subjected to a working test until the fuel cell enters a standby mode (zero load mode) again, and a power data fitting curve of the fuel cell is acquired by a control unit and is shown in FIG. 5.
As shown in fig. 5, after the distributed energy system enters the operating mode, it is monitored that the battery capacity is less than SOCmin, the fuel cell gradually increases the power output until the maximum output power is maintained, and after the battery capacity is greater than SOCmax, the fuel cell decreases the power output and enters the standby mode.
Battery charging and discharging current threshold value test
And (3) connecting the test prototype platform to an electronic load, setting the test prototype platform to be in a constant power mode, adjusting the capacity of the storage battery to 70%, starting a system for testing, executing a storage battery capacity threshold value control strategy and a storage battery charging and discharging current control strategy, and monitoring a power output curve of the fuel battery and a storage battery capacity curve as shown in FIGS. 6 a-6 c.
Referring to fig. 6a, when the system is started, it is monitored that the SOC of the storage battery fed back by the energy storage unit is lower than SOCmin, so that the control unit increases the output power of the fuel cell and continues until the capacity of the storage battery is SOCmin, monitors that the charging current Ic is greater than the set fluctuation value I, starts to reduce the power output of the fuel cell, and completes the automatic matching of the load. And then, simulating load change to suddenly increase the power of the electronic load to 3.8kW and reduce the power of the electronic load to 1kW respectively for testing, wherein the results are shown in FIGS. 6b and 6c, the SOC of the storage battery is within a set threshold value, the charging and discharging current of the storage battery exceeds an allowable fluctuation value I due to sudden change of the load, the control unit immediately adjusts the power of the fuel cell and gradually approaches to balance operation, and automatic tracking and matching of the load are realized.
Through test verification, each working mode of the developed novel distributed energy system works normally, and the proposed control strategy completely meets the adaptability of the distributed energy system to different loads and load changes.
As a further improvement based on the distributed energy system, as shown in fig. 7, an embodiment of the present invention provides an energy control method for a distributed energy system, where the distributed energy system is composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system, and a control system, and the method is executed by the control system, and includes the following steps:
s1, detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
in the embodiment, the energy storage unit in the energy storage system is charged after the energy conversion output of photovoltaic energy/wind energy and the like is stabilized by the control system (value V0), the battery output voltage stabilization value of the fuel cell power generation system is set to be V1, and the rated voltage value of the energy storage unit is set to be V; then in one embodiment, the priority control policy of the control system is:
V0>V1>Vforehead (forehead)
Wherein, V0 and V1 must be within the allowable charging voltage range of the storage battery, and it is suggested to adopt a wide voltage input DC module to charge the storage battery, as described in FIG. 8 and steps S2-S5.
S2, when the output voltage of the renewable energy power generation system is larger than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system to generate power;
specifically, when the output voltage of the solar photovoltaic power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, the fuel cell power generation system is turned off, and a photovoltaic input relay of the solar photovoltaic power generation system is turned on, so that the solar photovoltaic power generation system is connected to the renewable energy power generation system.
And when the output voltage of the wind power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a wind energy input relay of the wind power generation system so as to connect the wind power generation system to the renewable energy power generation system.
S3, when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
s4, when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel power generation system;
and S5, when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and increasing the output power of the fuel cell power generation system to cooperatively output power.
Referring to fig. 9, the present invention further provides an energy control device of a distributed energy system, where the distributed energy system is composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system, and a control system, the energy control device includes a control module, the control module is configured to control a fuel supply module, a fuel cell module, an energy storage module, a photovoltaic/wind power conversion module, and the like, and the control module is configured to:
detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation;
when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel power generation system;
and when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power.
The following tests and analyses were performed based on the above protocol:
according to an energy control method of the distributed energy system, a 4kW distributed energy system test prototype is developed. The rated output power of the fuel cell is 4kW, the output voltage is set to 54V through a voltage-stabilizing isolation power supply, the energy storage unit is a 48V100Ah standard lithium battery module with BMS management and communication, the maximum output power is 5kW, the SOCmin is set to be 70%, the SOCmax is set to be 85%, and the allowable charging and discharging current fluctuation value I is set to be 3A.
Multi-level energy priority testing
The photovoltaic simulator is connected to a 3.2 system test platform and is set to be 2kW, the load is set to be 4kW, the SOC of the storage battery is 70%, and then the system is started and the power output of the fuel cell and the capacity change curve of the storage battery are monitored.
As shown in fig. 10, it can be seen from the power of the fuel cell that when the battery capacity reaches above the set SOCmin, and it is monitored that the charging current exceeds the allowable fluctuation I, the control unit automatically adjusts the output power of the fuel cell until the output power is output in coordination with the power of the input end of the photovoltaic simulator, and it can be seen that the priority of the input of the photovoltaic simulator is higher than that of the output of the fuel cell.
In summary, the embodiment of the invention integrates the energy sources such as the fuel cell power generation system, the solar photovoltaic power generation system and the wind power generation system, and realizes the tracking of the system to the load power by monitoring the state of charge (SOC), the charging and discharging current state and the like of the storage battery in the energy storage system, thereby further realizing the dynamic adjustment of the fuel cell power, and effectively avoiding the hysteresis of the fuel cell power change and the large-amplitude power fluctuation in the power compensation process. Furthermore, by adopting a multi-level energy voltage threshold priority strategy, the low-cost energy such as photovoltaic and the like in the energy system is connected into a priority power supply mode, so that the cooperative control among the energy systems such as fuel cells, photovoltaic, wind power and the like is favorably realized, the energy utilization efficiency is improved, and the cost is reduced.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (8)

1. An energy control method of a distributed energy system, wherein the distributed energy system is composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system and a control system, the method comprises the following steps:
detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation;
when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel cell power generation system;
and when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power.
2. The method according to claim 1, wherein the output voltage of the renewable energy power generation system and the output regulated voltage of the fuel cell power generation system are each greater than a battery charging voltage rating of the energy storage system.
3. The energy control method of the distributed energy system according to claim 1 or 2, wherein the renewable energy power generation system comprises a solar photovoltaic power generation system; when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation, specifically:
and when the output voltage of the solar photovoltaic power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a photovoltaic input relay of the solar photovoltaic power generation system so as to connect the solar photovoltaic power generation system into the renewable energy power generation system.
4. The energy control method of the distributed energy system according to claim 1 or 2, wherein the renewable energy generation system includes a wind energy generation system; when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, specifically:
and when the output voltage of the wind power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a wind energy input relay of the wind power generation system so as to connect the wind power generation system to the renewable energy power generation system.
5. An energy control apparatus of a distributed energy system, the distributed energy system being composed of a fuel cell power generation system, a renewable energy power generation system, an energy storage system, and a control system, the energy control apparatus comprising a control module configured to:
detecting the output voltage of the renewable energy power generation system in real time, and comparing the output voltage of the renewable energy power generation system with the output voltage stabilization value of the fuel cell power generation system;
when the output voltage of the renewable energy power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, controlling the distributed energy system to be connected to the renewable energy power generation system for power generation;
when the output voltage of the renewable energy power generation system is smaller than the output voltage stabilization value of the fuel cell power generation system, judging whether the output power of the renewable energy power generation system is within a preset load demand power range;
when the output power of the renewable energy power generation system is within the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system for power generation, and reducing the output power of the fuel cell power generation system or closing the fuel cell power generation system;
and when the output power of the renewable energy power generation system does not belong to the preset load demand power range, controlling the distributed energy system to be connected into the renewable energy power generation system, and improving the output power of the fuel cell power generation system to cooperatively output power.
6. The energy control device of a distributed energy system according to claim 5, wherein the output voltage of the renewable energy power generation system and the output regulated voltage of the fuel cell power generation system are each greater than a battery charging voltage rating of the energy storage system.
7. The energy control device of the distributed energy system according to claim 5 or 6, wherein the renewable energy power generation system comprises a solar photovoltaic power generation system; the control module further configured to:
and when the output voltage of the solar photovoltaic power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a photovoltaic input relay of the solar photovoltaic power generation system so as to connect the solar photovoltaic power generation system into the renewable energy power generation system.
8. The energy control device of the distributed energy system according to claim 5 or 6, wherein the renewable energy power generation system comprises a wind power generation system; the control module further configured to:
and when the output voltage of the wind power generation system is greater than or equal to the output voltage stabilization value of the fuel cell power generation system, shutting down the fuel cell power generation system, and opening a wind energy input relay of the wind power generation system so as to connect the wind power generation system to the renewable energy power generation system.
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