CN111953016A - Mobile multi-energy micro-grid control method and system - Google Patents
Mobile multi-energy micro-grid control method and system Download PDFInfo
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- CN111953016A CN111953016A CN202010729461.8A CN202010729461A CN111953016A CN 111953016 A CN111953016 A CN 111953016A CN 202010729461 A CN202010729461 A CN 202010729461A CN 111953016 A CN111953016 A CN 111953016A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/30—The power source being a fuel cell
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- 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
- H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
- H02J2310/50—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads
- H02J2310/56—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads characterised by the condition upon which the selective controlling is based
- H02J2310/58—The condition being electrical
- H02J2310/60—Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
- Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
-
- 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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- 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
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
- Y04S20/20—End-user application control systems
- Y04S20/222—Demand response systems, e.g. load shedding, peak shaving
Abstract
The invention discloses a mobile multi-energy micro-grid control method and a system, wherein a storage battery or a diesel engine generator set is independently started to serve as a main power supply according to the state of charge (SOC) of the storage battery; after the micro-grid system is started, the fuel cell generator set is started to work, if the fuel cell generator set is stable, the fuel cell generator set serves as a main power supply of the micro-grid system, and in the second stage, the photovoltaic cell generator set, the fuel cell generator set, the storage battery and the mutual combined power generation of the photovoltaic cell generator set, the fuel cell generator set and the storage battery meet the load demand power Pload(ii) a If the fuel cell generator set is unstable, the photovoltaic cell generator set, the storage battery, the diesel engine generator set and the mutual combined power generation thereof are used for meeting the load demand power Pload. The invention can realize the advantage of combining renewable energy sources with a micro-grid systemAnd the energy utilization of the movable micro-grid is realized.
Description
Technical Field
The invention relates to the technical field of power supply equipment, in particular to a mobile multi-energy micro-grid control method and system.
Background
In the utilization of renewable energy power generation, wind power, photovoltaic power generation and the like are influenced by meteorological factors, have intermittence and random fluctuation, lead to output power fluctuation, bring non-negligible negative effects to a power grid, and can stabilize the power fluctuation of the renewable energy power generation caused by the meteorological factors by designing an energy storage device.
A Micro-Grid (Micro-Grid) is a small power generation and distribution system, can be used for realizing reliable supply of various energy forms with different loads, and is an effective mode for realizing an active power distribution network. Because the direct current micro-grid system mainly depends on the mutual cooperation of the direct current conversion units to work, when one direct current conversion unit fails, the whole micro-grid system can be unstable or even crashed. Therefore, when the number of the direct current conversion units configured in the microgrid system is large, the failure probability of the microgrid system is multiplied, and the reliability of the microgrid system is influenced.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a mobile multi-energy microgrid control method and system, so that the advantages of combining renewable energy sources with a microgrid system are realized, and the energy sources of a mobile microgrid are utilized.
The technical scheme adopted by the invention is as follows:
a mobile multi-energy micro-grid control method comprises the following steps:
s1, in the micro-grid starting stage, the storage battery or the diesel engine generator set is independently started to be used as a main power supply to supply power according to the state of charge (SOC) of the storage battery, and the micro-grid system is started;
s2, the micro-grid system starts and then enters a first stage, the fuel cell generator set starts to work, and power P of the fuel cell is used for the micro-grid systemfcJudging whether the output power of the fuel cell generator set is stable or not, and entering a second stage if the output power of the fuel cell generator set is stable; if the fuel cell generator set is unstable, the photovoltaic cell generator set, the storage battery, the diesel engine generator set and the mutual combined power generation thereof are used for meeting the load demand power Pload。
S3, second stage: when the output power of the fuel cell generator set is stable, the fuel cell is indicatedWhen the generator set can work normally, the fuel cell generator set is used as a main power supply of the microgrid system, and in the second stage, the photovoltaic cell generator set, the fuel cell generator set, the storage battery and the mutual combined power generation thereof meet the load demand power Pload。
Further, in S2, if the storage power is used as the main power supply and the photovoltaic cell generator set can normally operate, the control process includes:
if Pload＜Ppv_preAnd SOC<SOCmaxThe photovoltaic cell generator set is in the constant voltage working mode Ppv_preThe point is that the output load end supplies power and charges the storage battery with redundant electric energy; if Pload＜Ppv_preAnd SOC > SOCmaxThe photovoltaic cell generator set works in a power following mode and supplies power to an output load end; ppv_preFor photovoltaic cell generator set power, SOC is the state of charge of the battery, SOCmaxRespectively is the upper limit value of the charge capacity of the storage battery;
if Pload＜Ppv_maxAnd SOC < SOCminThe photovoltaic cell generator set is in the MPPT mode to supply power to the output load end 3 and charge the storage battery with redundant power of the photovoltaic cell generator set; if Pload＜Ppv_maxAnd SOCminIf the SOC is less than or equal to the SOC, the photovoltaic cell generator set is in a power following mode; ppv_maxIs the maximum power generation power, SOC, of the photovoltaic generator setminThe lower limit value of the charge capacity of the storage battery;
if Ppv_max＜PloadThe photovoltaic cell generator set and the storage battery are jointly used for generating power, and the discharge power P of the storage batteryba＝Pload-Ppv_max(ii) a If Pba＜PmaxThe storage battery discharges in the constant-voltage working mode; if Pba＝Pba_maxThe battery is operated in a P/Q control mode, Pba_maxThe maximum generated power of the storage battery;
if Ppv_max+Pba＜PloadThen the power generation is carried out by combining the diesel engine generator set, and the power generation power of the diesel engine generator set is Pdiesel＝Pload-Pba_max-Ppv_max；
If Pdiesel+Pba_max+Ppv_max＜PloadJudging whether a controllable load exists or not, if so, cutting off the controllable load and prompting that the load is overlarge; and if the controllable load does not exist, the switch is disconnected to stop power supply, and the overload is prompted.
In S2, if the storage battery is used as the main power supply and the photovoltaic cell generator set can not work normally, the control process is as follows:
if Pload＜Pba_maxIf the load end is not connected with the storage battery, the storage battery supplies power to the load end independently;
if Pba_max＜PloadThen starting the diesel engine generator set and the storage battery to jointly generate power, wherein the power of the diesel engine generator set is Pdiesel＝Pload-Pba_max；
If Pdiesel+Pba_max＜PloadIf the controllable load exists, the control system cuts off the controllable load to prompt that the load is overlarge; and if the controllable load does not exist, the control system cuts off the switch, the power supply of the microgrid system is stopped, and the overload is prompted.
If the diesel engine generator set is used as a main power supply and the photovoltaic cell generator set can normally work, the control process is as follows:
if Pload＜Ppv_maxIf the photovoltaic cell generator set can meet the end power requirement, the photovoltaic cell generator set is in the MPPT working mode to independently supply power to the load end, and the redundant power of the photovoltaic cell generator set is used for charging the storage battery;
if Ppv_max＜PloadThe photovoltaic cell generator set and the diesel engine generator set jointly generate power, and the output power of the diesel engine generator set is Pdiesel＝Pload-Ppv_max；
If Pdiesel+Ppv_max＜PloadThen determine if there isThe controllable load is cut off to prompt that the load is too large if the controllable load exists; if the controllable load does not exist, the load switch is cut off, power supply is stopped, and the condition that the load is too large is indicated.
In S2, if the diesel generator set is used as a main power supply and the photovoltaic cell generator set cannot work normally, the control process is as follows:
if Pload＜PdieselThe diesel engine generator set can meet the end power requirement, and the diesel engine generator set supplies power independently;
if Pdiesel＜PloadJudging whether a controllable load exists, if so, cutting off the controllable load to prompt that the load is overlarge; if the controllable load does not exist, the load switch is cut off, power supply is stopped, and the condition that the load is too large is indicated.
Further, in S3, the switching rule between the power generation units in the second stage is:
s3.1, when the photovoltaic cell generator set can work normally, and P ispv_pre＞PloadThe photovoltaic cell generator set is in a constant-voltage working mode to independently supply power to the load, the SOC of the storage battery is judged, and if the SOC is metmin＜SOC＜SOCmaxOr SOCminIf the voltage is more than SOC, the photovoltaic cell generator set is in a constant voltage working mode and charges the storage battery; if P isload＜Ppv_maxAnd judging that the SOC is satisfiedmin＜SOC＜SOCmaxOr SOCminThe photovoltaic cell generator set is in an MPPT mode, and the redundant power of the photovoltaic cell generator set is used for charging the storage battery, and the charging power of the storage battery is Pcharge＝Ppv_max-Pload。
S3.2, if Ppv_max＜PloadRequiring the combined generation of a fuel cell generator set and a photovoltaic cell generator set if Pfc+Ppv_max＞PloadAnd SOC is less than or equal to SOCminIf the fuel cell generator set and the photovoltaic cell generator set are in the MPPT mode to supply power to the load end, the storage battery is charged until the SOC is more than or equal to the SOCmaxStopping charging; if SOCmin＜SOC＜SOCmaxThe fuel cell generator set and the photovoltaic cell generator set are used for supplying power jointly, the photovoltaic cell generator set (11) works in an MPPT mode to output the maximum power, and the power P of the fuel cell generator setfc＝Pload- Ppv_maxIf P isfc＜Pfc_preThe fuel cell generator set is at Pfc_prePoint work, and charging the storage battery by using redundant power; if Pfc＜Pfc_maxThe fuel cell generator set is in a power following mode;
s3.3, if Pfc_max+Ppv_max＜PloadThen a fuel cell generator set, a photovoltaic cell generator set and a storage battery are needed to jointly generate electricity; explaining that the joint power generation power of the fuel cell generator set and the photovoltaic cell generator set does not meet the power P required by the loadloadThen, the SOC status of the battery at this time needs to be analyzed, which is specifically as follows:
when SOC < SOCminThe storage battery can not normally supply power, and the fuel cell generator set and the photovoltaic cell generator set need to be combined with a diesel engine generator set; if Pdiesel+Pfc_max+Ppv_max＞PloadThe output power of the fuel cell generator set, the photovoltaic cell generator set and the diesel engine generator set can meet the load power requirement, and the output power of the diesel engine generator set is Pdiesel＝Pload-Pfc_max-Ppv_max(ii) a If Pdiesel+Pfc_max+Ppv_max＜PloadAnd if the controllable load exists, the controllable load is cut off and the overload is prompted. If the controllable load does not exist, the load end control switch is cut off, power supply is stopped, and the condition that the load is too large is provided;
if SOC > SOC is satisfiedminIf the storage battery can supply power normally, the power is supplied by the combination of the fuel cell generator set, the photovoltaic cell generator set and the storage battery, and the output work of the storage batteryA rate of Pba＝Pload-Pfc_max-Ppv_max(ii) a If Pba+Pfc_max+Ppv_max＜PloadThe situation that the combined power supply of the fuel cell generator set, the photovoltaic cell generator set and the storage battery is not enough to meet the load power demand is shown, the fuel cell generator set, the photovoltaic cell generator set and the storage battery need to be combined with a diesel generator set, and the output power of the diesel generator set is Pdiesel＝Pload-Pfc_max-Ppv_max-Pba(ii) a If Pdiesel+Pfc_max+Ppv_max+Pba＜PloadAnd if the output power of the fuel cell generator set, the photovoltaic cell generator set, the storage battery and the diesel engine generator set cannot meet the load power requirement, checking whether a controllable load exists at a load end, and if the controllable load exists, cutting off the controllable load and prompting that the load is overlarge. And if the controllable load does not exist, the load end control switch is cut off, the power supply is stopped, and the overload is prompted. The above working mode is a control method for normal work of the whole microgrid system.
Further, the method for regulating and controlling sudden reduction of the load power of the microgrid system comprises the following steps: the current load power PloadComparing the output power of the power generation unit on the power generation side when P isfc+Ppv+Pdiesel＞PloadWhen, if SOC is less than SOCmaxThe diesel generator 14 continues to work, the storage battery 5 stops working and enters a charging state, and the storage battery 5 absorbs redundant power to perform charging work; if SOC is not less than SOCmaxIf the energy storage capacity of the storage battery 5 is not enough to maintain power balance or the energy storage device 13 is charged to saturation, the diesel generator set 14 enters a shutdown state, and the storage battery 5 works in place of the diesel generator set 14;
when P is presentfc+Ppv+Pdiesel＜PloadWhen, if SOC > SOCminThen the storage battery 5, the fuel cell generator set 12, the diesel engine generator set 14 and the photovoltaic cell generator set 11 supply power to the load together; if SOC is less than SOCminJudging whether a controllable load exists in the microgrid system, if so, cutting off the controllable load and prompting the loadToo large a load; if the controllable load does not exist in the system, the cut-off switch stops supplying power, and the overload is prompted.
Further, the method for regulating and controlling sudden increase of the load power of the microgrid system comprises the following steps: when P is presentfc+Ppv+Pdiesel+Pbat＜ PloadIf the controllable load exists at the load end, the control system cuts off the controllable load and prompts that the load is overlarge; if the controllable load does not exist at the load end, the control system cuts off the switch at the load end, stops supplying power and prompts that the load is too large.
Further, the method for regulating the abnormity of the power generation end of the microgrid system comprises the following steps: the power generation unit with the fault is emergently disconnected from the power distribution system, and the fault of the power generation unit is prompted; meanwhile, the total generated power P of other generating units is judgedtotalWhether the whole microgrid system can be supported to normally work or not is judged, and if P is judgedtotal＞PloadIf the remaining power generation units can be supported, the connection between the power generation units and the power distribution system is only broken; if Ptotal＜PloadIf the controllable load exists, the controllable load is disconnected and the overload is prompted; if the controllable load does not exist, the switch of the load end 3 is disconnected to stop power supply, and the overload is prompted.
Further, the method for regulating and controlling the black start of the microgrid system comprises the following steps: detecting the current SOC of the storage battery 5, if SOC is more than SOCminThe diesel engine generator set 14 and the storage battery 5 are jointly used for supplying power, and the limited electric energy only supports important loads and drives other power generation units to generate power; if SOC is less than SOCminIf so, the diesel engine generator set 14 works alone to output power, and the storage battery stops charging and discharging; after the black start, the diesel generator set 14 and the storage battery 5 or the diesel generator set 14 drive the fuel cell 12 and the photovoltaic generator set 11 to start, the start stage is restarted to recover to the normal working process, and the working modes of the first stage and the second stage are returned.
A mobile multi-energy microgrid system comprises a DG unit 1 on a direct current side, a power distribution system 2, an output load end 3 and a microgrid central control system 4; the direct current side DG unit 1 comprises a photovoltaic cell generator set 11, a fuel cell generator set 12, an energy storage device 13 and a diesel engine generator set 14; the low-voltage direct-current bus is connected with a first DC-DC converter 15, a second DC-DC converter 16, a bidirectional circulation DC-DC converter 17 and an AC-DC converter 18 of a direct-current side DG unit 1 respectively, the low-voltage direct-current bus is connected with a medium-voltage direct-current bus through a booster 21, and the medium-voltage direct-current bus is connected with an output load end 3; the output load end 3 comprises an alternating current load and a direct current load; the microgrid central control system 4 is respectively connected with each component in the direct current side DG unit 1, the power distribution system 2 and the output load end 3 through a CAN bus; and controls the work switching of the dc side DG unit 1, the distribution system 2, and the output load terminal 3.
The invention has the beneficial effects that:
the fuel cell is used as a main power supply, the fuel cell has the characteristics of high efficiency, small pollution and strong adaptability, the working advantage of the fuel cell is amplified when the fuel cell is used as a fixed power generation unit, and the power generation of the fuel cell is efficient and stable through a control system; according to the hierarchical control system provided by the invention, the data is processed by collecting the real-time data of the micro-grid system, and the micro-grid system is scheduled through a mathematical model, so that the micro-grid system has flexible expansibility and flexibility; the invention establishes the storage battery energy management system, accurately manages the capacity of the storage battery by collecting the information of the storage battery, completes the intelligent control of the energy storage system and ensures the stable and reliable operation of the spring mud system.
Drawings
FIG. 1 is a schematic diagram of a mobile multi-energy microgrid system of the present invention;
fig. 2 is a structural diagram of the bidirectional circulation converter 17;
FIG. 3 is a flowchart illustrating the start-up control of the mobile multi-energy microgrid system of the present invention;
FIG. 4 is a control flow diagram of a stage in which a 1 st-order in-battery cell is used as a primary power supply;
FIG. 5 is a control flow diagram of the stage of the diesel generator as the primary power source in stage 1;
fig. 6 is a control flow chart of the stage 2 fuel cell as the main power supply;
fig. 7 is a control flow diagram when a fault occurs within the microgrid system;
fig. 8 is a flowchart illustrating the microgrid system being powered off in a black start state;
in the figure, 1, a direct current side DG unit, 2, a power distribution system, 3, an output load end, 4, a microgrid central control system, 5, a storage battery, 6, a super capacitor, 11, a photovoltaic cell generator set, 12, a fuel cell generator set, 13, an energy storage device, 14, a diesel generator set, 15, a first DC-DC converter, 16, a second DC-DC converter, 17, a bidirectional circulation DC-DC converter, 18, an AC-DC converter, 21, a booster, 22, a DC-AC converter, 23, a third DC-DC converter, 24, an AC-AC converter, 31, a first alternating current load, 32, a second alternating current load, 33, a first direct current load, 34 and a second direct current load.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The mobile multi-energy microgrid system disclosed by the invention is shown in fig. 1 and specifically comprises a direct-current side DG unit 1, a power distribution system 2, an output load end 3 and a microgrid central control system 4. The direct current side DG unit 1 comprises a photovoltaic cell generator set 11, a fuel cell generator set 12, an energy storage device 13 and a diesel engine generator set 14; the output end of the photovoltaic cell generator set 11 is connected with a first DC-DC converter 15 through a lead, the output end of the fuel cell generator set 12 is connected with a second DC-DC converter 16 through a lead, the output end of the energy storage device 13 is connected with a bidirectional circulating DC-DC converter 17 through a lead, the output end of the diesel generator set 14 is connected with an AC-DC converter 18 through a lead, and the first DC-DC converter 15, the second DC-DC converter 16, the bidirectional circulating DC-DC converter 17 and the AC-DC converter 18 are all connected with the power distribution system 2.
The power distribution system 2 comprises a low-voltage direct-current bus, a medium-voltage direct-current bus and an alternating-current bus, wherein the low-voltage direct-current bus is respectively connected with a first DC-DC converter 15, a second DC-DC converter 16, a bidirectional circulating DC-DC converter 17 and an AC-DC converter 18 of the DG unit 1 at the direct-current side, the low-voltage direct-current bus is connected with the medium-voltage direct-current bus through a booster 21, and the medium-voltage direct-current bus is connected with the output load end 3.
The output load end 3 comprises an alternating current load and a direct current load, the alternating current load comprises a first alternating current load 31 and a second alternating current load 32, and more specifically, a DC-AC converter 22, an alternating current bus and an AC-AC converter 24 are sequentially connected in series between a medium-voltage direct current bus and the first alternating current load 31; a DC-AC converter 22 and an AC bus are connected in series between the medium voltage DC bus and the second AC load 32 in sequence. The direct-current loads comprise a first direct-current load 33 and a second direct-current load 34, and a third DC-DC converter 23 is sequentially connected in series between the medium-voltage direct-current bus and the first direct-current load 33; the medium voltage dc bus is directly connected to the first dc load 33. And circuit switches are passed through for connection of the respective loads, denoted by K1, K2, K3 and K4, respectively. Through the four circuits, four voltage requirements of 48/220V direct current voltage and 220/380V alternating current voltage at the output end are met.
The microgrid central control system 4 is respectively connected with each component in the direct current side DG unit 1, the power distribution system 2 and the output load end 3 through a CAN bus; the microgrid central control system 4 is used for acquiring information such as output end load power demand, voltage on a current bus, SOC of a storage battery, generating power of a photovoltaic generator set, generating power of a fuel cell and the like, and controlling work switching of the direct current side DG unit 1, the power distribution system 2 and the output load end 3.
The energy storage device 13 comprises a storage battery 5 and a super capacitor 6, and a complementary working mode is carried out between the storage battery 5 and the super capacitor 6 through a bidirectional circulating DC-DC converter 17; the bidirectional circulation DC-DC converter 17 adopts a Buck-Boost converter, as shown in FIG. 2, the storage battery 5 and the super capacitor 6 are both provided with the same bidirectional converter, and the storage battery 5 and the super capacitor 6 are both connected with a low-voltage direct-current bus through the bidirectional converters.
In the working process, firstly, a voltage threshold value of the low-voltage direct-current bus is set, when the voltage of the low-voltage direct-current bus exceeds the threshold value (the rated voltage of the direct-current bus is 10%), the bidirectional circulation DC-DC converter 17 works in a Buck mode, the super capacitor 6 absorbs redundant electric energy from the low-voltage direct-current bus to charge, the super capacitor 6 has good transient response, if the voltage of the low-voltage direct-current bus is only overhigh for a short time, the super capacitor is only used, and if the voltage of the low-voltage bus still exceeds the threshold value after the super capacitor is fully charged, the storage battery 5 absorbs electric energy from the; when the voltage of the direct-current bus is lower than a threshold value (the rated voltage of the direct-current bus is 10%), the bidirectional circulation DC-DC converter 17 works in a Boost mode, the energy storage device transmits the electric energy stored by the super capacitor 6 to the low-voltage direct-current bus, and after the electric energy of the super capacitor 6 is discharged, the storage battery 5 transmits the electric energy to the low-voltage bus; the bidirectional circulation DC-DC converter 17 is controlled by a Pulse Width Modulation (PWM) technology, so that two semiconductor devices work, drive signals are sent out in different time periods, a bidirectional converter formed by the bidirectional converter of the super capacitor 6 and the bidirectional converter formed by the storage battery 5 work at different moments, and the super capacitor 6 and the storage battery 5 can perform a complementary working mode.
The battery 5 has a constant power control mode (P/Q control mode) and a constant voltage (V/F) control mode. When the constant power control is adopted, the active power and reactive power references of the bidirectional circulating DC-DC converter 17 can be set according to the external power requirement, so that the supply and demand balance is achieved. The constant power control mode can be divided into two links: an outer loop power control link and an inner loop current control link. When the outer loop control is carried out in a P/Q control mode, comparing the reference value of the output or input power of the set converter with an actual value, and entering the compared error into a PI controller to obtain a current reference value controlled by an inner loop; the current inner loop control enables the actual current and the control current signal to be adjusted through the PI controller, and the output power is stable. When the storage battery works in the constant voltage mode, the constant voltage control mode can be divided into two links: in the voltage outer ring, comparing the set reference frequency and reference voltage with the collected bus frequency and bus voltage, and respectively obtaining current reference values controlled by the output inner ring through the difference value of the two values through a PI (proportional-integral) controller; the inner ring collects a difference value between a current signal and a reference current, and outputs a modulation signal through PI regulation, so that the stability of output voltage is ensured.
Because too big charge-discharge power of battery 5 can cause the injury to battery 5, reduces battery 5 life, and the ageing that can accelerate battery 5 of discharging too deeply or charging too much simultaneously, consequently need carry out necessary control to the charge-discharge power of battery 5, specific constraint algorithm is as follows:
Pcharge≤Pcharge_max
Pdischarge≤Pdischarge_max
SOCmin≤SOC≤SOCmax
in the formula: pchargeAnd PdischargeRespectively the charging power and the discharging power of the storage battery; pcharge_maxAnd Pdischarge_maxRespectively the maximum charge allowable power and the maximum discharge allowable power of the storage battery; SOC is the charge of the storage battery; SOCminAnd SOCmaxThe lower limit value and the upper limit value of the charge capacity of the storage battery are respectively.
The photovoltaic cell generator set 11 is limited by weather factors due to photovoltaic power generation, and power generation has volatility and intermittency, so that the photovoltaic power generation can only be used as a driven power generation unit, and a constraint algorithm is designed according to normal working time:
PPV_min≤Ppv≤PPV_max
-PPV≤ΔPPV≤PPV_re-PPV
in the formula: ppvThe operating power of the photovoltaic generator set; pPV_minThe minimum starting power of the photovoltaic generator set; pPV_maxThe rated power of the photovoltaic generator set; delta PPVAdjusting the power value of the photovoltaic generator set; pPV_reAnd predicting the power generation capacity of the photovoltaic cell in a super-short period.
Diesel generator set 14, when diesel generator set 14 operating power is less, the fuel can not burn completely, and 14 generating efficiency of diesel generator set is lower to the oil consumption is great this moment, can high-efficient economic operation in order to guarantee diesel generator, need set up the constraint of diesel generator minimum generated power:
Pdiesel_min≤Pdiesel≤Pdiesel_max
in the formula: pdieselFor operating power of diesel-electric generator sets, Pdiesel_minMinimum starting power, P, of the diesel unitdiesel_maxThe maximum power value is output by the diesel engine generator set.
A mobile multi-energy micro-grid control method comprises the following steps:
s1, start stage: when the whole microgrid is started to work, as the fuel cell needs time to react to reach a stable power generation state, the photovoltaic power generation also needs reaction time, and the photovoltaic power generation amount is not stable; therefore, when the microgrid is started, a stable and reliable power supply source is taken as a main power supply source, the storage battery 5 or the diesel generator set 14 is independently started in the starting stage to supply power to the whole microgrid, and the judgment basis for power supply by taking the storage battery 5 or the diesel generator set 14 as the main power supply source in the starting stage is as follows: after receiving a micro-grid starting signal, acquiring the state of charge (SOC) of the storage battery 5; determining the state of SOC of the storage battery 5, as shown in fig. 3;
if SOC is less than SOCminIf the micro-grid system is started, the diesel generator set 14 serves as a main power supply to start the micro-grid system;
if SOCminIf the SOC is less than or equal to the SOC, the storage battery 5 serves as a main power supply to start the microgrid system;
therein, SOCminAnd SOCmaxAnd respectively selecting a main power supply in a starting stage according to the state of the SOC of the storage battery.
S2, first stage: when the storage battery or the diesel generator set 14 serves as a main power supply, the microgrid system is started; during this phase, the fuel cell generator set 12 is started to perform preheating operation according to the fuel cell power PfcJudging whether the fuel cell generator set 12 is stable (namely whether the output power is stable near a set value), and entering the second step if the fuel cell generator set 12 is stableTwo stages; if the fuel cell generator set 12 is unstable, whether the photovoltaic cell generator set 11, the storage battery 5, the diesel engine generator set 14 and the mutual combined power generation thereof meet the load power requirement is sequentially judged.
S2.1, when the storage battery 5 is used as a main power supply as shown in the figure 4, judging whether the photovoltaic cell generator set 11 can normally work or not according to whether the photovoltaic cell generator set 11 can generate electric energy or not; according to the load demand power PloadPower P of photovoltaic cell generator setpv_preThe relationship of (c) is controlled.
In case 5, if it is stated that the combined power generation of the storage battery 5, the photovoltaic cell generator set 11 and the diesel generator set 14 cannot meet the load demand power PloadIf the controllable load exists, the control system 4 cuts off the controllable load to prompt that the load is too large; and if the controllable load does not exist, the switch is disconnected to stop power supply, and the overload is prompted.
S2.2, when the storage battery 5 serves as a main power supply and the photovoltaic cell generator set 11 cannot work normally, power P is required according to the loadloadPower P to batterybaThe relationship (2) performs operation control.
S2.3, if the diesel engine generator set 14 is used as a main power supply in the figure 5, judging whether the photovoltaic cell generator set 11 can work normally according to whether the photovoltaic cell generator set 11 can generate electric energy; according to the load demand power PloadPower P of generator set with photovoltaic cellpv_preThe relationship of (c) is controlled.
S2.4, when the diesel generator set 14 serves as a main power supply and the photovoltaic cell generator set 11 cannot work normally, power P is required according to the loadloadGenerating power P with diesel generator set 14dieselControl ofAnd (5) preparing.
S3, second stage: the output power of the fuel cell generator set 12 is already stable, and when the fuel cell generator set 12 can normally work, the fuel cell generator set 12 is used as a main power supply of the microgrid system as shown in fig. 6; the switching rule among the power generation units in the second stage is as follows:
s3.1, when the photovoltaic cell generator set 11 can normally generate electricity and work, the micro-grid central control system 4 judges the output power P of the photovoltaic cell generator set 11pv_preWhether the power P required by the load can be metloadIf P is satisfiedpv_pre＞PloadThe load is supplied with power by the photovoltaic cell generator set 11 alone and the photovoltaic cell generator set 11 is in the constant voltage operation mode. If the load demands power Pload＜Ppv_max(ii) a Judging the SOC of the storage battery 5, and if the SOC is less than the SOCmaxThe photovoltaic cell generator set 11 is in a constant voltage working mode and charges the storage battery 5; if SOC < SOC is satisfiedminThe photovoltaic power generator set 11 is in the MPPT mode (i.e., the maximum power mode), and charges the storage battery with the excess power of the photovoltaic power generator set 11, where the charging power of the storage battery is Pcharge＝Ppv_max-Pload。
S3.2, if the maximum generating power P of the photovoltaic cell generator set 11pv_max＜PloadWhen the photovoltaic cell generator set 11 is not enough to supply power to the whole microgrid system, the microgrid central control system 4 controls the fuel cell generator set 12 and the photovoltaic cell generator set 11 to jointly generate power. If Pfc+Ppv_max＞PloadDescription of the Fuel cell Generator set 12 and photovoltaic PowerThe combined power generation power of the pool generator set 11 meets the load demand power PloadFurther judging the SOC state of the storage battery, if the SOC is less than or equal to the SOCminThe fuel cell generator set 12 and the photovoltaic cell generator set 11 are in the MPPT mode, and supply more surplus power to the storage battery 5 until the SOC of the storage battery 5 is more than or equal to the SOCmaxStopping charging; if SOC > SOCminThen, the fuel cell generator set 12 and the photovoltaic cell generator set 11 jointly supply power, the photovoltaic cell generator set 11 works in the MPPT mode to output the maximum power, and the power P of the fuel cell generator set 12fc＝Pload-Ppv_maxIf P isfc＜Pfc_preThe fuel cell generator set 12 is at Pfc_prePoint work, and the redundant power is used for charging the storage battery 5; if Pfc＜Pfc_maxThe fuel cell genset 12 is in power following mode.
S3.3, when Pfc_max+Ppv_max＜PloadThe combined power generation of the fuel cell generator set 12 and the photovoltaic cell generator set 11 not meeting the load demand power P is explainedloadIf so, the SOC status of the storage battery 5 needs to be analyzed, and it is determined whether the storage battery 5 can jointly generate power with the fuel cell generator set 12 and the photovoltaic cell generator set 11 to satisfy the load demand power Pload. The specific process is as follows:
when SOC < SOCminAt this time, the storage battery 5 cannot normally supply power, and the fuel cell generator set 12 and the photovoltaic cell generator set 11 need to be combined with the diesel engine generator set 14; if Pd esel+Pfc_max+Ppv_max＞PloadIt is stated that the output powers of the fuel cell generator set 12, the photovoltaic cell generator set 11 and the diesel generator set 14 can meet the load power requirement, and the output power of the diesel generator set 14 is P at this timediesel＝Pload-Pfc_max-Ppv_max(ii) a If Pdiesel+Pfc_max+Ppv_max＜PloadIf the output power of the fuel cell generator set 12, the photovoltaic cell generator set 11 and the diesel engine generator set 14 cannot meet the load power requirement, the output power is not enoughThe microgrid central control system 4 checks whether a controllable load exists at the load end, and if the controllable load exists, the controllable load is cut off and the overload is prompted. And if the controllable load does not exist, the load end control switch is cut off, the power supply is stopped, and the overload is prompted. The above working mode is a control method for normal work of the whole microgrid system.
If SOC > SOC is satisfiedminWhen the storage battery 5 can normally supply power, the fuel cell generator set 12, the photovoltaic cell generator set 11 and the storage battery 5 jointly supply power, and the output power of the storage battery 5 is Pba＝Pload-Pfc_max- Ppv_max(ii) a If Pba_max+Pfc_max+Ppv_max＜PloadIt is explained that the combined power supply of the fuel cell generator set 12, the photovoltaic cell generator set 11 and the storage battery 5 is not enough to meet the load power demand, and the fuel cell generator set 12, the photovoltaic cell generator set 11 and the storage battery 5 need to be combined with the diesel generator set 14, and the output power of the diesel generator set 12 is Pdiesel＝Pload-Pfc_max-Ppv_max-Pba_max(ii) a If Pdiesel+Pfc_max+Ppv_max+Pba_max＜PloadAnd if the output power of the fuel cell generator set 12, the photovoltaic cell generator set 11, the storage battery 5 and the diesel generator set 14 cannot meet the load power requirement, the microgrid central control system 4 checks whether a controllable load exists at the load end, and cuts off the controllable load and prompts that the load is too large if the controllable load exists. And if the controllable load does not exist, the load end control switch is cut off, the power supply is stopped, and the overload is prompted. The above working mode is a control method for normal work of the whole microgrid system.
Aiming at faults which may occur when the whole microgrid system works, such as sudden load fluctuation (sudden load increase or sudden load decrease) at a load end and sudden working faults of a power generation unit (DG unit), the invention also provides a series of regulation and control methods, and the specific processes are as follows:
as shown in fig. 7, when the load at the load end fluctuates and the power demand is unstable, the microgrid central control system 4 starts a checking procedure to determine whether the load fluctuation is smaller or larger.
If the load power is suddenly reduced, the microgrid central control system 4 enables the current load power P to be obtainedloadComparing the output power of the power generation unit on the power generation side, and if the output power satisfies Pfc+Ppv+Pdiesel＞PloadIllustrates the load demand power PloadWhen the sum of the generated power of the fuel cell generator set 12, the photovoltaic cell generator set 11 and the diesel engine generator set 14 is less than the sum of the generated power of the micro-grid central control system 4, judging whether the SOC value of the storage battery is less than the SOC value or notmaxIf SOC < SOCmaxThe diesel generator 14 continues to work, the storage battery 5 stops working and enters a charging state, and the storage battery 5 absorbs redundant power to perform charging work; if SOC is not less than SOCmaxIf the energy storage capacity of the storage battery 5 is not enough to maintain the power balance or the energy storage device 13 is fully charged, the diesel-electric generator set 14 enters a shutdown state, and the storage battery 5 works in place of the diesel-electric generator set 14.
When P is presentfc+Ppv+Pdiesel＜PloadWhen, if SOC > SOCminThe storage battery (5), the fuel cell generator set (12), the diesel engine generator set (14) and the photovoltaic cell generator set (11) supply power to the load together; if SOC is less than SOCminIf the controllable load exists in the microgrid system, the controllable load is cut off, and the overload is prompted; if the controllable load does not exist in the system, the cut-off switch stops supplying power, and the overload is prompted.
If the load end is suddenly connected to a high-power load device, the load power is suddenly increased; the microgrid central control system 4 is according to Pfc+Ppv+Pdiesel+Pbat＜PloadJudging the power P required by the loadloadWhether the power is more than the sum of the power generated by the fuel cell generator set 12, the photovoltaic cell generator set 11, the diesel engine generator set 14 and the storage battery 5, if the load needs power PloadGreater than Pfc+Ppv+Pdiesel+PbatThe microgrid central control system 4 judges whether controllable loads exist in the microgrid system or not, and if the controllable loads exist at the load ends, the control system can be switched offControlling the load and prompting that the load is too large; and if the controllable load does not exist at the load end, the control system cuts off the switch at the load end, stops supplying power and prompts that the load is overlarge.
When the direct current side DG unit 1 is abnormal, namely the power generation unit suddenly drops out of the working state, the microgrid central control system 4 emergently disconnects the problem power generation unit in the direct current side DG unit 1 from the power distribution system 2, and prompts the power generation unit to break down. Secondly, the microgrid central control system 4 judges the total generated power P of other generating units of the direct current side DG unit 1totalWhether the whole microgrid system can be supported to normally work or not is judged, and if P is judgedtotal＞PloadThe remaining power generation units can support and only break the connection between the problem development power unit and the power distribution system; if Ptotal＜PloadThen, it is determined whether there is a controllable load at the output load terminal 3. If the controllable load exists, the microgrid central control system 4 disconnects the controllable load and prompts that the load is too large; if the controllable load does not exist, the micro-grid central control system 4 cuts off the switch of the load end 3 to stop supplying power, and the load is prompted to be too large.
When the microgrid central control system 4 detects that the microgrid system is in a black start state, the microgrid central control system 4 detects the current SOC value of the storage battery, and if SOC is more than SOCminThe diesel generator set 14 and the storage battery 5 are supplied with power jointly, but the power is limited to only support important loads (mainly meeting the requirement of power above 220V) and drive other power generation units to generate power; if SOC is less than SOCminAnd if the power is not output, the diesel generating set 14 works alone to output power, and the storage battery stops charging and discharging.
After the black start, the diesel generator set 14 and the storage battery 5 or the diesel generator set 14 drive the fuel cell 12 and the photovoltaic generator set 11 to start, the start stage is restarted to recover to the normal working process, and the working modes of the first stage and the second stage are returned.
According to the invention, through designing the control process aiming at the black start, when the micro-grid system is suddenly electrified due to a fault, the S4 control layer is triggered to respond, the whole micro-grid system is taken over to drive the unstable power generation unit to generate power by utilizing the start with the self-starting capability in the system, the power generation capability is expanded, and the working capability of the micro-grid system is gradually recovered.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.
Claims (8)
1. A mobile multi-energy micro-grid control method is characterized by comprising the following steps:
s1, in the micro-grid starting stage, the storage battery (5) or the diesel generator set (14) is independently started to be used as a main power supply to supply power and start the micro-grid system according to the state of charge (SOC) of the storage battery (5);
s2, the micro-grid system starts and then enters a first stage, the fuel cell generator set (12) starts to work, and the micro-grid system starts to work according to the power P of the fuel cellfcJudging whether the output power of the fuel cell generator set (12) is stable, and entering a second stage if the output power of the fuel cell generator set (12) is stable; if the fuel cell generator set (12) is unstable, the photovoltaic cell generator set (11), the storage battery (5), the diesel engine generator set (14) and the mutual combination thereof generate electricity to meet the load demand power Pload。
S3, second stage: when the output power of the fuel cell generator set (12) is stable, which indicates that the fuel cell generator set (12) can normally work, the fuel cell generator set (12) is used as a main power supply of the microgrid system, and in the second stage, the photovoltaic cell generator set 11, the fuel cell generator set (12), the storage battery (5) and the mutual combined power generation thereof meet the load demand power Pload。
2. The method for controlling the mobile multi-energy micro-grid according to claim 1, wherein in the step S2, if the electricity storage (5) is used as a main power supply and the photovoltaic cell generator set (11) can work normally, the control process comprises:
if Pload＜Ppv_preAnd SOC < SOCmaxThe photovoltaic cell generator set (11) is in the P state according to the constant voltage working modepv_preThe point is that the output load end (3) supplies power and charges the storage battery (5) with redundant electric energy; if Pload＜Ppv_preAnd SOC > SOCmaxThe photovoltaic cell generator set (11) works in a power following mode and supplies power to the output load end (3); ppv_preFor photovoltaic cell generator set power, SOC is the state of charge of the accumulator (5), SOCmaxRespectively is the upper limit value of the charge capacity of the storage battery;
if Pload＜Ppv_max]And SOC < SOCmaxThe photovoltaic cell generator set (11) is in an MPPT mode to supply power to the output load end 3 and charge the storage battery (5) with redundant power of the photovoltaic cell generator set (11); if Pload＜Ppv_maxAnd SOCmaxIf the SOC is less than or equal to the SOC, the photovoltaic cell generator set (11) is in a power following mode; ppv_maxIs the maximum power generation power, SOC, of the photovoltaic generator set (11)maxThe upper limit value of the charge capacity of the storage battery;
if Ppv_max＜PloadThe photovoltaic cell generator set (11) and the storage battery (5) are combined to generate electricity, and the discharge power P of the storage battery (5)ba＝Pload-Ppv_max(ii) a If Pba＜Pba_maxIf so, the storage battery (5) discharges in a constant-voltage working mode; if Pba＝Pba_maxThe battery is operated in a P/Q control mode, Pba_maxThe maximum generated power of the storage battery;
if Ppv_max+Pba_max＜PloadThen the power is generated by combining the diesel generating set (14), and the generated power of the diesel generating set (14) is Pdiesel＝Pload-Pba_max-Ppv_max；
If Pdiesel+Pba_max+Ppv_max＜PloadJudging whether a controllable load exists or not, if so, cutting off the controllable load and prompting that the load is overlarge; and if the controllable load does not exist, the switch is disconnected to stop power supply, and the overload is prompted.
In the step S2, if the storage battery (5) is used as a main power supply and the photovoltaic cell generator set (11) cannot work normally, the control process is as follows:
if Pload＜Pba_maxIf the load end is not connected with the storage battery (5), the storage battery (5) supplies power to the load end independently;
if Pba_max＜PloadThen the diesel generator set (14) and the storage battery (5) are started to jointly generate electricity, and the power of the diesel generator set (14) is Pdiesel＝Pload-Pba_max；
If Pdiesel+Pba_max＜PloadIf the power of the storage battery (5) and the diesel generator set (14) cannot meet the power requirement of the load end, judging whether a controllable load exists or not, and if the controllable load exists, cutting off the controllable load by the control system to prompt that the load is overlarge; and if the controllable load does not exist, the control system cuts off the switch, the power supply of the microgrid system is stopped, and the overload is prompted.
If the diesel generator set (14) is used as a main power supply and the photovoltaic cell generator set (11) can normally work, the control process is as follows:
if Pload＜Ppv_maxWhen the photovoltaic cell generator set (11) can meet the end power requirement, the photovoltaic cell generator set (11) is in the MPPT working mode to independently supply power to the load end, and the redundant power of the photovoltaic cell generator set (11) is used for charging the storage battery (5);
if Ppv_max＜PloadThe photovoltaic cell generator set (11) and the diesel engine generator set (14) jointly generate electricity, and the output power of the diesel engine generator set (14) is Pdiesel＝Pload-Ppv_max；
If Pdiesel+Ppv_max＜PloadJudging whether a controllable load exists or not, and if the controllable load exists, cutting off the controllable load to prompt that the load is overlarge; if the controllable load does not exist, the load switch is cut off, power supply is stopped, and the condition that the load is too large is indicated.
In the step S2, if the diesel generator set (14) is used as the main power supply and the photovoltaic cell generator set (11) cannot normally operate, the control process includes:
if Pload＜PdieselThe diesel engine generator set (14) can meet the end power requirement, and the diesel engine generator set (14) supplies power independently;
if Pdiesel＜PloadJudging whether a controllable load exists, if so, cutting off the controllable load to prompt that the load is overlarge; if the controllable load does not exist, the load switch is cut off, power supply is stopped, and the condition that the load is too large is indicated.
3. The method as claimed in claim 2, wherein in step S3, the switching rule between the power generating units in the second stage is:
s3.1, when the photovoltaic cell generator set (11) can work normally, and P ispv_pre＞PloadThe photovoltaic cell generator set (11) is in a constant-voltage working mode to supply power for the load independently, the SOC of the storage battery (5) is judged, and if the SOC is metmin＜SOC＜SOCmaxOr SOCminIf the voltage is more than SOC, the photovoltaic cell generator set (11) is in a constant voltage working mode and charges the storage battery (5); if P isload＜Ppv_maxAnd judging that the SOC is satisfiedmin＜SOC＜SOCmaxOr SOCminThe photovoltaic cell generator set (11) is in an MPPT mode when the SOC is higher than the SOC, and the redundant power of the photovoltaic cell generator set (11) is used for charging the storage battery, and the charging power of the storage battery is Pcharge＝Ppv_max-Pload。
S3.2, if Ppv_max＜PloadThe fuel cell generator set (12) and the photovoltaic cell generator set (11) are required to jointly generate power if Pfc+Ppv_max＞PloadAnd SOC is less than or equal to SOCminThe fuel cell generator set (12) and the photovoltaic cell generator set (11) are in the MPPT mode to supply power to the load end, and the storage battery (5) is charged until the SOC is more than or equal to the SOCmaxStopping charging; if SOCmin＜SOC＜SOCmaxThe fuel cell generator set (12) and the photovoltaic cell generator set (11) are used for supplying power jointly, and the photovoltaic cell generator set (11) works in the MPPT mode to output the maximum powerPower, power P of the fuel cell generator set (12)fc＝Pload-Ppv_maxIf P isfc＜Pfc_preThe fuel cell generator set (12) is at Pfc_prePoint work, and the redundant power charges the storage battery (5); if Pfc＜Pfc_maxThe fuel cell generator set (12) is in a power following mode;
s3.3, if Pfc_max+Ppv_max＜PloadIf so, the fuel cell generator set 12, the photovoltaic cell generator set 11 and the storage battery 5 are required to jointly generate power; the combined power generation power of the fuel cell generator set 12 and the photovoltaic cell generator set 11 does not meet the load demand power PloadThen, the SOC status of the battery 5 at this time needs to be analyzed, which is specifically as follows:
when SOC < SOCminThe storage battery (5) can not normally supply power, and the fuel cell generator set (12) and the photovoltaic cell generator set (11) need to be combined with the diesel engine generator set (14); if Pdiesel+Pfc_max+Ppv_max＞PloadThe output power of the fuel cell generator set (12), the photovoltaic cell generator set (11) and the diesel engine generator set (14) can meet the load power requirement, and the output power of the diesel engine generator set (14) is P at the momentdiesel＝Pload-Pfc_max-Ppv_max(ii) a If Pdiesel+Pfc_max+Ppv_max＜PloadAnd if the output power of the fuel cell generator set (12), the photovoltaic cell generator set (11) and the diesel engine generator set (14) cannot meet the load power requirement, the microgrid central control system (4) checks whether a controllable load exists at a load end, and cuts off the controllable load and prompts that the load is too large if the controllable load exists. If the controllable load does not exist, the load end control switch is cut off, power supply is stopped, and the condition that the load is too large is prompted;
if SOC > SOC is satisfiedminThe storage battery (5) can normally supply power, and is jointly supplied with power by the fuel cell generator set (12), the photovoltaic cell generator set (11) and the storage battery (5), and the output power of the storage battery (5) is Pba＝Pload-Pfc_max-Ppv_max(ii) a If Pba+Pfc_max+Ppv_max＜PloadThe situation that the combined power supply of the fuel cell generator set (12), the photovoltaic cell generator set (11) and the storage battery (5) is not enough to meet the load power demand is explained, the combined power supply needs to be combined with the diesel generator set (14), and the output power of the diesel generator set (12) is Pdiesel＝Pload-Pfc_max-Ppv_max-Pba(ii) a If Pdiesel+Pfc_max+Ppv_max+Pba＜PloadAnd if the output power of the fuel cell generator set (12), the photovoltaic cell generator set (11), the storage battery (5) and the diesel engine generator set (14) cannot meet the load power requirement, whether a controllable load exists at a load end is checked, and if the controllable load exists, the controllable load is cut off and the load is indicated to be overlarge. And if the controllable load does not exist, the load end control switch is cut off, the power supply is stopped, and the overload is prompted. The above working mode is a control method for normal work of the whole microgrid system.
4. The method for controlling a mobile multi-energy microgrid according to claim 3, wherein in the step S3, the method for controlling the sudden reduction of the load power of the microgrid system comprises: the current load power PloadComparing the output power of the power generation unit on the power generation side when P isfc+Ppv+Pdiesel＞PloadWhen, if SOC is less than SOCmaxThe diesel generator (14) continues to work, the storage battery (5) stops working and enters a charging state, and the storage battery (5) is used for absorbing redundant power to perform charging work; if SOC is not less than SOCmaxIf the energy storage capacity of the storage battery (5) is not enough to maintain power balance or the energy storage device (13) is charged to saturation, the diesel generating set (14) enters a shutdown state, and the storage battery (5) replaces the diesel generating set (14) to work;
when P is presentfc+Ppv+Pdiesel＜PloadWhen, if SOC > SOCminThe storage battery (5), the fuel cell generator set (12), the diesel engine generator set (14) and the photovoltaic cell generator set (11) supply power to the load together; if SOC is less than SOCminAnd then judging whether the microgrid system is in the microgrid systemIf the controllable load exists in the system, the controllable load is cut off, and the overload is prompted; if the controllable load does not exist in the system, the cut-off switch stops supplying power, and the overload is prompted.
5. The method for controlling the mobile multi-energy microgrid according to claim 3, wherein in the step S3, the method for controlling the load power of the microgrid system to suddenly increase is as follows: when P is presentfc+Ppv+Pdiesel+Pbat＜PloadIf the controllable load exists at the load end, the control system cuts off the controllable load and prompts that the load is overlarge; and if the controllable load does not exist at the load end, the control system cuts off the switch at the load end, stops supplying power and prompts that the load is overlarge.
6. The method according to claim 3, wherein in step S3, the method for controlling the occurrence of the abnormality at the power generation end of the microgrid system comprises: the method comprises the following steps of emergently disconnecting a failed power generation unit from a power distribution system, and prompting the power generation unit to fail; meanwhile, the total generated power P of other generating units is judgedtotalWhether the whole microgrid system can be supported to normally work or not is judged, and if P is judgedtotal＞PloadIf the remaining power generation units can be supported, the connection between the power generation units and the power distribution system is only broken; if Ptotal＜PloadIf so, judging whether a controllable load exists at the output load end, and if so, disconnecting the controllable load and prompting that the load is overlarge; if the controllable load does not exist, the switch of the load end (3) is disconnected to stop power supply, and the overload is prompted.
7. The method according to claim 3, wherein in the step S3, the method for controlling the black start of the microgrid system comprises: detecting the current SOC of the storage battery (5), if SOC is more than SOCminThe diesel generator set (14) and the storage battery (5) are supplied with power jointly, and the limited electric energy only supports important loads and drives other power generation unitsGenerating electricity; if SOC is less than SOCminIf the power is output by the independent work of the diesel engine generator set (14), the storage battery stops charging and discharging; after the black start, the diesel generator set (14) and the storage battery (5) or the diesel generator set (14) drive the fuel cell (12) and the photovoltaic generator set (11) to start, the start stage is restarted to recover to a normal working process, and the working modes of the first stage and the second stage are returned.
8. A mobile multi-energy microgrid system comprises a direct current side DG unit (1), a power distribution system (2), an output load end (3) and a microgrid center control system (4); the direct current side DG unit (1) comprises a photovoltaic cell generator set (11), a fuel cell generator set (12), an energy storage device (13) and a diesel engine generator set (14); the low-voltage direct-current bus is connected with a first DC-DC converter (15), a second DC-DC converter (16), a bidirectional circulation DC-DC converter (17) and an AC-DC converter (18) of a direct-current side DG unit (1) respectively, the low-voltage direct-current bus is connected with a medium-voltage direct-current bus through a booster (21), and the medium-voltage direct-current bus is connected with an output load end (3); the output load end 3 comprises an alternating current load and a direct current load; the microgrid central control system (4) is respectively connected with each component of the direct current side DG unit (1), the power distribution system (2) and the output load end (3) through the CAN bus, and controls the work switching of the direct current side DG unit (1), the power distribution system (2) and the output load end (3).
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