CN110880759A - Energy management method and system of light storage micro-grid based on real-time electricity price mechanism - Google Patents

Energy management method and system of light storage micro-grid based on real-time electricity price mechanism Download PDF

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Publication number
CN110880759A
CN110880759A CN201911167135.6A CN201911167135A CN110880759A CN 110880759 A CN110880759 A CN 110880759A CN 201911167135 A CN201911167135 A CN 201911167135A CN 110880759 A CN110880759 A CN 110880759A
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power
energy storage
storage system
grid
real
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丁贤兵
琚洋
杨宗军
邹绍琨
张彦虎
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Hefei Sunshine Amperex Technology Ltd
Hefei Sungrow New Energy Technology Co Ltd
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Hefei Sunshine Amperex Technology 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
    • H02J3/008—Circuit arrangements for ac mains or ac distribution networks involving trading of energy or energy transmission rights
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
    • 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

Abstract

The application discloses a light storage micro-grid based on a real-time electricity price mechanism and an energy management method and system thereof, so as to realize the economical efficiency and safety of the operation of the light storage micro-grid. The method comprises the following steps: judging whether the light storage micro-grid transmits power to the power grid reversely, if so, closing each power conversion module in the light storage micro-grid; if the power is not transmitted to the power grid reversely, judging whether the power consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period; if so, then: if the power absorbed by the optical storage microgrid from the power grid is enough to meet the local load power requirement, the local load power requirement is preferentially met, the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system, if the local load power requirement is not met, the superposed part of the photovoltaic power generation power preferentially meets the local load power requirement, and the photovoltaic residual power is charged to the energy storage system; if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.

Description

Energy management method and system of light storage micro-grid based on real-time electricity price mechanism
Technical Field
The invention relates to the technical field of electric power and energy, in particular to a light storage microgrid based on a real-time electricity price mechanism and an energy management method and system thereof.
Background
The light storage micro-grid is a small local area power grid comprising a power generation, transmission, distribution and utilization management system and consisting of distributed photovoltaic devices, energy storage devices and local loads, is connected to the power grid through a unique PCC (point of common coupling), and can be operated in a grid-connected mode or an independent mode.
Under a real-time electricity price mechanism, how to realize the economy and the safety of the operation of the light storage micro-grid is a target always pursued by technical personnel in the field.
Disclosure of Invention
In view of this, the invention provides an optical storage microgrid and an energy management method and system thereof based on a real-time electricity price mechanism, so as to realize the economy and safety of the operation of the optical storage microgrid under the real-time electricity price mechanism.
An energy management method of a light storage micro-grid based on a real-time electricity price mechanism comprises the following steps:
judging whether the light storage micro-grid transmits power to the power grid backwards or not;
if the condition of backward power transmission to the power grid occurs, closing each power conversion module in the light storage micro-grid;
if the condition of reversely transmitting power to the power grid does not occur, judging whether the power consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period;
if so, then: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the power requirement of the local load is not met, the superposed part of the photovoltaic power generation power preferentially meets the power requirement of the local load, and the photovoltaic residual power generation power charges the energy storage system;
if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.
Optionally, the power absorbed by the optical storage microgrid from the power grid is equal to the effective capacity of a transformer in the optical storage microgrid.
Optionally, when the power absorbed by the optical storage microgrid from the power grid is equal to the effective capacity of a transformer in the optical storage microgrid, and the power consumption cost of the energy storage system in the current period is greater than the electricity purchase price in the current period:
if the energy storage system is in the charging state in the last period of time, the target power P is obtained when the energy storage system is charged in the current period of timeess_target＝Pess_real+ΔPPV+Ptrans_eff-PPCC；
If the energy storage system is in a discharging state or does not execute charging and discharging actions in the last period of time, Pess_target＝Ptrans_eff+ΔPPV-Pess_real-PPCC；
Wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; ptrans_effRepresenting the effective capacity of the transformer; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
Optionally, when the power absorbed by the optical storage microgrid from the power grid is equal to the effective capacity of a transformer in the optical storage microgrid, and the power consumption cost of the energy storage system in the current period is not greater than the electricity purchase price in the current period:
if the energy storage system in the last period is in a discharging state, the target power P is obtained when the energy storage system in the current period is dischargedess_target＝PPCC+Pess_real-ΔPPV；
If the energy storage system is in a charging state or does not perform charging and discharging actions in the last period of time, the target power P is obtained when the energy storage system is discharged in the current period of timeess_target＝PPCC-Pess_real-ΔPPV；
Wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
Optionally, the energy storage system includes n online energy storage converters, where n is greater than or equal to 1, the ith energy storage battery is connected to the ith online energy storage converter, i is 1, 2, …, and n, and outputs of the online energy storage converters are connected in parallel;
the upper limit value of the charging power of the energy storage system is
Figure BDA0002287746860000021
The lower limit value of the discharge power of the energy storage system is
Figure BDA0002287746860000022
Wherein, PPCS_ratedFor nominal power, U, of energy-storing convertersPCSi_DCThe dc voltage of the ith online energy storage converter,
Figure BDA0002287746860000031
the current is limited for charging the ith energy storage battery,
Figure BDA0002287746860000032
the maximum allowable charging power of the energy storage system is obtained;
Figure BDA0002287746860000033
the current is limited for the discharge of the ith energy storage cell,
Figure BDA0002287746860000034
the maximum allowable discharge power of the energy storage system.
Optionally, before determining whether the electricity consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period, the method further includes:
and judging that the increase rate or the decrease rate of the electricity purchasing price in the current time period exceeds a set threshold value.
Optionally, in the charging and discharging process of the energy storage system, the method further includes:
detecting the SOC value of an energy storage battery in the energy storage system, and stopping the energy storage system from performing charging and discharging actions when the SOC is less than SOC1 or SOC is more than SOC 2; the SOC1 is the lower discharge limit of the energy storage system, and the SOC2 is the upper charge limit of the energy storage system.
An energy management system of a light storage microgrid based on a real-time electricity price mechanism comprises:
the anti-reverse power transmission unit is used for judging whether the light storage micro-grid transmits power to the power grid reversely; if the condition of backward power transmission to the power grid occurs, closing each power conversion module in the light storage micro-grid;
the energy management unit is used for judging whether the power consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period or not when the condition of backward power transmission to the power grid does not occur; if so, then: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the power requirement of the local load is not met, the superposed part of the photovoltaic power generation power preferentially meets the power requirement of the local load, and the photovoltaic residual power generation power charges the energy storage system; if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.
Optionally, the power absorbed by the optical storage microgrid from the power grid is equal to the effective capacity of the transformer in the optical storage microgrid.
Optionally, the energy management unit is further configured to determine that an increase rate or a decrease rate of the electricity purchase price in the current time period exceeds a set threshold before determining whether the electricity consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period.
According to the technical scheme, when the reverse power transmission from the light storage micro-grid to the power grid is detected, the power conversion module in the whole light storage micro-grid is closed, so that the reverse power transmission from the energy storage system to the power grid is avoided, and the running safety of the light storage micro-grid is realized. Moreover, on the premise of preferentially ensuring the power supply of the local load, the energy storage system is charged and discharged according to the principle of high electricity purchasing cost, low electricity purchasing cost and low electricity charging, so that the economical efficiency of the operation of the light storage micro-grid is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of an energy management method for an optical storage microgrid based on a real-time electricity price mechanism, disclosed in an embodiment of the present invention;
fig. 2 is a schematic diagram of an optical storage microgrid structure according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an energy management system of an optical storage microgrid based on a real-time electricity price mechanism, disclosed in 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.
Referring to fig. 1, an embodiment of the present invention discloses an energy management method for an optical storage microgrid based on a real-time electricity price mechanism, including:
step S01: judging whether the light storage micro-grid transmits power to the power grid or not, and if so, entering the step S02; if not, the process proceeds to step S03.
Step S02: and turning off each power conversion module in the light storage microgrid, and then returning to the step S01.
Specifically, fig. 2 shows a typical structure diagram of an optical storage microgrid, wherein: the photovoltaic system and the energy storage system are subjected to alternating current coupling and then are subjected to confluence through a confluence cabinet, and a confluence output point is connected to a local load on one hand and is connected to a power grid through a transformer and a PCC (point-to-point capacitor) on the other hand. The photovoltaic system measures photovoltaic power generation power (or electric quantity) through a photovoltaic electric meter, the energy storage system measures charge and discharge power (or electric quantity) through an energy storage electric meter, and the PCC electric meter measures PCC point power (or electric quantity); and the EMS (energy management system) controls each power conversion module in the optical storage microgrid according to the readings of the photovoltaic electric meter, the energy storage electric meter and the PCC electric meter, so that the energy flow of the whole optical storage microgrid is managed.
In order to improve the electricity utilization safety, a power grid company definitely prohibits the energy storage system from transmitting electricity back to the power grid. However, in the light storage microgrid, the photovoltaic system also transmits power back to the power grid, and the PCC electricity meter cannot distinguish whether the energy storage system transmits power back to the power grid or the photovoltaic system transmits power back to the power grid. In order to completely avoid the situation that the energy storage system transmits power backwards to the power grid, the embodiment of the invention immediately closes the power conversion module in the whole light storage microgrid when the PCC ammeter indicates that the light storage microgrid transmits power backwards to the power grid.
Optionally, when other faults or abnormalities occur in the optical storage microgrid, the embodiment of the invention may also turn off the power conversion module in the whole optical storage microgrid.
Optionally, when the power conversion module in the whole optical storage microgrid is turned off, the optical storage microgrid sends a corresponding alarm prompt, and the alarm prompt may inform operation and maintenance personnel or clients in a form of a short message.
Step S03: judging whether the electricity consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period; if yes, go to step S04; if not, the process proceeds to step S05.
Specifically, the energy storage system is charged and discharged according to the principle that the electricity purchasing cost is high and low, when the electricity purchasing cost in the current time period is higher than the electricity consumption cost of the energy storage system, the discharging condition of the energy storage system is considered to be met, and when the electricity purchasing cost in the current time period is lower than the electricity consumption cost of the energy storage system, the charging condition of the energy storage system is considered to be met, so that the economy of operation of the light storage micro-grid is favorably realized.
Step S04: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the local load power requirement is not met, the superposed part of photovoltaic power generation power preferentially meets the local load power requirement, and the photovoltaic residual power generation power charges the energy storage system. Thereafter, the process returns to step S01.
Specifically, the light-storage microgrid absorbs power from a power grid through a transformer, and the transformer has effective capacity limitation, so that the maximum value of the power that the light-storage microgrid can absorb from the power grid is the effective capacity of the transformer. Setting the effective capacity of the transformer to Ptrans_effThen according to formula Ptrans_eff＝Ptrans_rated*Rate*|PPFPCCI can be calculated to obtain Ptrans_effA value of (1), wherein Ptrans_ratedFor rated capacity of transformer, Rate is derating coefficient, PPFPCCIs the PCC point power factor.
When the charging condition of the energy storage system is met, the embodiment of the invention supplies power to the local load in the optical storage microgrid and charges the energy storage system by using the power absorbed by the optical storage microgrid from the power grid and the photovoltaic power generation power. The embodiment of the invention recommends that the power absorbed by the optical storage microgrid from the power grid is the maximum value Ptrans_effTherefore, the maximum charging amount of the energy storage system in a short time of electricity price change is guaranteed, and the light-storage microgrid user obtains higher electricity price difference benefits. In addition, the charging power of the energy storage system in the current period is not only influenced by the effective capacity P of the transformertrans_effThe constraints of (a) are also related to whether the energy storage system was charged or discharged in the previous period.
EMS in the micro-grid system calculates target power P of the energy storage system in the current time period based on the constraint conditionsess_target(Pess_targetPositive value when the energy storage system is charged and negative value when the energy storage system is discharged), the energy storage system is enabled to act according to P at the current time interval by controlling the power conversion module in the optical storage microgrid to actess_targetCharging or discharging is performed. Next, in setting the light storageThe power absorbed by the network from the network is equal to the effective capacity P of the transformertrans_effOn the premise that the target power P is given when the energy storage system is charged in the current time period according to the two conditions of charging and discharging of the energy storage system in the previous time periodess_targetAnd (3) calculating:
1) last period energy storage system charging
If the energy storage system is in a charging state in the previous period, the energy flow of the whole optical storage microgrid in the previous period meets the following formula (1):
Pload_real＝PPCC-Pess_real+PPVformula (1)
Wherein, Pload_realRepresenting the power required by the local load; pPCCRepresenting the power absorbed by the light storage microgrid from the power grid in the last period; pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; pPVAnd representing the photovoltaic power generation power in the last period.
The energy flow of the whole light storage microgrid in the current period meets the following formula (2):
Ptrans_eff+PPV_now＝Pload_real+Pess_targetformula (2)
Wherein, PPV_nowRepresenting the photovoltaic power generation power at the current time.
By combining the above formula (1) and formula (2), the following formula (3) can be obtained:
Pess_target＝Pess_real+ΔPPV+Ptrans_eff-PPCCformula (3)
Wherein: delta PPV＝PPV_now-PPVAnd the difference value between the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period is represented.
EMS calculates target power P when energy storage system is charged in current time periodess_targetSatisfies the above formula (3), and at this time: when P is presentload_real＜Ptrans_effThat is, when the power absorbed by the optical storage microgrid from the power grid is enough to meet the power demand of the local load, the power absorbed by the optical storage microgrid from the power grid preferentially supplies power to the local load, and the residual power is superposedCharging the energy storage system by using all the photovoltaic power generation power in the previous period; when P is presentload_real＞Ptrans_effWhen the power absorbed by the optical storage micro-grid from the power grid is not enough to meet the local load power requirement, the photovoltaic power generation power of the power superposition part absorbed by the optical storage micro-grid from the power grid preferentially meets the local load power requirement, and the photovoltaic residual power generation power charges the energy storage system.
2) Last period energy storage system discharge (or not executing charge and discharge action)
The local load is supplied with power by the photovoltaic system, the energy storage system and the power grid together in the last period, and the energy flow of the whole light storage micro-grid meets the following formula (4):
Pload_real＝PPCC+Pess_real+PPVformula (4)
The energy storage system needs to be changed from a discharged state to a charged state at the present time. The energy flow of the whole light storage microgrid in the current time period meets the above formula (2).
Combining the above formula (4) and formula (2), the following formula (5) can be obtained:
Pess_target＝Ptrans_eff+ΔPPV-Pess_real-PPCCformula (5)
EMS calculates target power P when energy storage system is charged in current time periodess_targetSatisfies the above equation (5), and now: when P is presentload_real＜Ptrans_effIn time, the power P absorbed by the light storage micro-grid from the power gridPCCPreferentially supplying power to a local load, and overlapping all photovoltaic power generation power in the current time period with the residual power to charge the energy storage system; when P is presentload_real＞Ptrans_effDuring the process, the photovoltaic power generation power of the power superposition part absorbed by the light storage micro-grid from the power grid preferentially meets the local load power demand, and the photovoltaic residual power generation power charges the energy storage system.
Step S05: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met. Thereafter, the process returns to step S01.
Specifically, when the discharge condition of the energy storage system is met, the embodiment of the invention utilizes the photovoltaic power generation power and the energy storage system to supply power to the local load in the optical storage microgrid,the amount of discharge power of the energy storage system in the current period is related to whether the energy storage system was charged or discharged in the previous period. In the following, the target power P when the energy storage system is discharged in the current time period is given for the two cases of charging and discharging the energy storage system in the previous time period respectivelyess_targetAnd (3) calculating:
1) last period energy storage system discharge
The energy flow of the whole light storage micro-grid in the last period of time meets the above formula (4).
The energy flow of the whole light storage microgrid in the current period meets the following formula (6):
PPV_now+Pess_target＝Pload_realformula (6)
By combining the above equations (4) and (6), the target power P calculated by the EMS during the discharging of the energy storage system in the current period can be obtainedess_targetComprises the following steps:
Pess_target＝PPCC+Pess_real-ΔPPVformula (7)
2) Charging the energy storage system (or not executing charging and discharging actions) in the last period
The energy flow of the whole light storage micro-grid in the last period meets the above formula (1).
The energy storage system needs to be switched from a charging state to a discharging state in the current time period, and the energy flow of the whole light storage micro-grid meets the formula (6). By combining the above equations (1) and (6), the target power P calculated by the EMS during the discharging of the energy storage system in the current period can be obtainedess_targetComprises the following steps:
Pess_target＝PPCC-Pess_real-ΔPPVformula (8)
As can be seen from the above description, in the embodiment of the present invention, when it is detected that the optical storage microgrid transmits power back to the power grid, the power conversion module in the entire optical storage microgrid is turned off, so that the power storage system is prevented from transmitting power back to the power grid, and the safety of the operation of the optical storage microgrid is realized. In addition, on the premise of preferentially ensuring the power supply of the local load, the embodiment of the invention carries out charging and discharging on the energy storage system according to the principle of high electricity purchasing cost, low electricity purchasing cost and charging, thereby realizing the economical efficiency of the operation of the light storage micro-grid.
In addition, to further ensure the operation of the light storage systemThe embodiment of the invention also relates to the target power P obtained by the calculationess_targetMultiple boundary constraints are set, and target power Pess_targetAnd when the boundary constraint condition is not met, correction is needed. The specific description is as follows:
the energy storage System comprises n online Power conversion modules, namely PCS (Power converter System), wherein n is larger than or equal to 1, the ith energy storage battery is connected to the ith online Power conversion module, i is 1, 2, … and n, and the output of each online Power conversion module is connected in parallel.
The energy storage system is subject to multiple power boundary conditions during charging: n PPCS_rated，
Figure BDA0002287746860000081
Wherein n is the online number of PCS, PPCS_ratedIs PCS nominal power, UPCSi_DCIs the direct-current voltage of the ith PCS,
Figure BDA0002287746860000082
the current is limited for charging the ith energy storage battery,
Figure BDA0002287746860000083
and (4) the maximum allowable charging power of the energy storage system. The upper limit value of the charging power of the energy storage system obtained by combining the multiple power boundary condition constraints is PchargeP at each charging calculated as described aboveess_targetShould not exceed PchargeTake the maximum value, that is to say Pess_targetThe calculated values corresponding to the formulas (3) and (5) do not exceed PchargeTaking the calculated value itself when exceeding PchargeIs corrected to be Pcharge。
Figure BDA0002287746860000091
Likewise, the energy storage system is also subject to multiple power boundary conditions when discharging: -n PPCS_rated，
Figure BDA0002287746860000092
Wherein:
Figure BDA0002287746860000093
the current is limited for the discharge of the ith energy storage cell,
Figure BDA0002287746860000094
the maximum allowable discharge power of the energy storage system. The lower limit value of the discharge power of the energy storage system obtained by combining the multiple power boundary condition constraints is PdischargeP at each discharge calculated as described aboveess_targetShould not exceed PchargeTake the minimum value, that is to say Pess_targetThe calculated values corresponding to the expressions (7) and (8) are not less than PchargeTaking the calculated value itself, when it is less than PchargeIs corrected to be Pcharge。
Figure BDA0002287746860000095
Optionally, before the step S03, the method further includes: judging whether the increase rate or the decrease rate of the electricity purchase price of the current time period exceeds a set threshold value h0If yes, go to step S03; if not, the process returns to step S01.
Specifically, assuming that the electricity purchasing price of the current time period is m and the electricity purchasing price of the previous time period is m ', the fluctuation rate of the electricity purchasing price of the current time period is equal to | (m-m ')/m ' |, and the embodiment of the present invention is in | (m-m ')/m ' | ≦ h0The energy storage battery charging and discharging device does not perform charging and discharging actions in time, so that the energy storage system is prevented from frequently performing the charging and discharging actions when pricing fluctuation is low, and the cycle service life of the energy storage battery is prolonged.
In addition, because the recycling frequency of the energy storage battery is related to the DOD, the recycling frequency of the energy storage battery can be greatly improved by keeping the fluctuation of the SOC (state of charge) of the energy storage battery in a preset protection interval [ SOC1, SOC2 ]. Based on the electricity price fluctuation rule, the embodiment of the invention also performs shallow charging and shallow discharging (in terms of battery capacity) while performing the above-mentioned low charging and high discharging (in terms of electricity price) operation on the energy storage battery, so as to increase the number of times of recycling of the energy storage battery by reducing the charging and discharging amount of the energy storage battery each time.
The SOC1 is a lower discharge limit of the energy storage system, and the SOC2 is an upper charge limit of the energy storage system, and may be (SOC2-SOC1)/SOC1 < 5%, for example.
The EMS checks the SOC value in real time, and when the SOC belongs to the SOC1 and the SOC2, the EMS controls the energy storage system to perform charging and discharging actions according to the calculated target power; when SOC < SOC1 or SOC > SOC2, the charging and discharging operations of the energy storage system are stopped.
Corresponding to the above method embodiment, the embodiment of the present invention further discloses an energy management system of a light storage microgrid based on a real-time electricity price mechanism, as shown in fig. 3, including:
the anti-reverse power transmission unit 100 is used for judging whether reverse power transmission to a power grid occurs in the light storage microgrid; if the condition of backward power transmission to the power grid occurs, closing each power conversion module in the light storage micro-grid;
the energy management unit 200 is configured to, when power is not transmitted back to the power grid, determine whether the power cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period; if so, then: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the power requirement of the local load is not met, the superposed part of the photovoltaic power generation power preferentially meets the power requirement of the local load, and the photovoltaic residual power generation power charges the energy storage system; if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.
Optionally, the power absorbed by the optical storage microgrid from the power grid is equal to the effective capacity of the transformer in the optical storage microgrid.
Optionally, the energy management unit 200 is specifically configured to, when the electricity consumption cost of the energy storage system is greater than the electricity purchase price in the current time period:
if the energy storage system is in the charging state in the last time period, the target power P is obtained according to the charging time of the energy storage system in the current time periodess_target＝Pess_real+ΔPPV+Ptrans_eff-PPCCCharging the energy storage system;
if the energy storage system is in a discharge state or does not execute charge-discharge action in the last period, pressing Pess_target＝Ptrans_eff+ΔPPV-Pess_real-PPCCCharging the energy storage system;
wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; ptrans_effRepresenting the effective capacity of the transformer; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
Optionally, the energy management unit 200 is specifically configured to, when the electricity consumption cost of the energy storage system is not greater than the electricity purchase price in the current time period:
if the energy storage system is in the discharging state in the last period, the target power P is obtained according to the discharging time of the energy storage system in the current periodess_target＝PPCC+Pess_real-ΔPPVDischarging the energy storage system;
if the energy storage system is in a charging state or does not execute charging and discharging actions in the last period of time, the target power P is obtained according to the discharging time of the energy storage system in the current period of timeess_target＝PPCC-Pess_real-ΔPPVDischarging the energy storage system;
wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
Optionally, the energy storage system includes n online energy storage converters, where n is greater than or equal to 1, the ith energy storage battery is connected to the ith online energy storage converter, i is 1, 2, …, and n, and outputs of the online energy storage converters are connected in parallel;
the energy management unit 200 is further configured to limit the upper limit value of the charging power of the energy storage system to be
Figure BDA0002287746860000111
The lower limit value of the discharge power of the energy storage system is
Figure BDA0002287746860000112
Wherein, PPCS_ratedFor nominal power, U, of energy-storing convertersPCSi_DCThe dc voltage of the ith online energy storage converter,
Figure BDA0002287746860000113
the current is limited for charging the ith energy storage battery,
Figure BDA0002287746860000114
the maximum allowable charging power of the energy storage system is obtained;
Figure BDA0002287746860000115
the current is limited for the discharge of the ith energy storage cell,
Figure BDA0002287746860000116
the maximum allowable discharge power of the energy storage system.
Optionally, in any energy management system disclosed above, the energy management unit 200 is further configured to determine that an increase rate or a decrease rate of the power purchase price in the current time period exceeds a set threshold before determining whether the power consumption cost of the energy storage system in the current time period is greater than the power purchase price in the current time period.
Optionally, in any energy management system disclosed above, the energy management unit 200 is further configured to detect an SOC value of an energy storage battery in the energy storage system during charging and discharging of the energy storage system, and stop the charging and discharging of the energy storage system when the SOC < SOC1 or SOC > SOC 2; the SOC1 is the lower discharge limit of the energy storage system, and the SOC2 is the upper charge limit of the energy storage system.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the energy management system disclosed by the embodiment, the description is simple because the energy management system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, the present embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. An energy management method of a light storage microgrid based on a real-time electricity price mechanism is characterized by comprising the following steps:
judging whether the light storage micro-grid transmits power to the power grid backwards or not;
if the condition of backward power transmission to the power grid occurs, closing each power conversion module in the light storage micro-grid;
if the condition of reversely transmitting power to the power grid does not occur, judging whether the power consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period;
if so, then: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the power requirement of the local load is not met, the superposed part of the photovoltaic power generation power preferentially meets the power requirement of the local load, and the photovoltaic residual power generation power charges the energy storage system;
if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.
2. The energy management method for the optical storage microgrid based on the real-time electricity price mechanism is characterized in that the power absorbed by the optical storage microgrid from a power grid is equal to the effective capacity of a transformer in the optical storage microgrid.
3. The energy management method of the light storage microgrid based on the real-time electricity price mechanism is characterized in that when the electricity consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period:
if the energy storage system is in the charging state in the last period of time, the target power P is obtained when the energy storage system is charged in the current period of timeess_target＝Pess_real+ΔPPV+Ptrans_eff-PPCC；
If the energy storage system is in a discharging state or does not execute charging and discharging actions in the last period of time, Pess_target＝Ptrans_eff+ΔPPV-Pess_real-PPCC；
Wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; ptrans_effRepresenting the effective capacity of the transformer; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
4. The energy management method of the light storage microgrid based on the real-time electricity price mechanism as claimed in claim 2, wherein when the electricity consumption cost of the energy storage system in the current time period is not greater than the electricity purchase price in the current time period:
if the energy storage system in the last period is in a discharging state, the target power P is obtained when the energy storage system in the current period is dischargedess_target＝PPCC+Pess_real-ΔPPV；
If the energy storage system is in a charging state or does not perform charging and discharging actions in the last period of time, the target power P is obtained when the energy storage system is discharged in the current period of timeess_target＝PPCC-Pess_real-ΔPPV；
Wherein, Pess_realFor the actual power of the energy storage system in the last period, Pess_realThe energy storage system is a positive value during charging and a negative value during discharging; delta PPVRepresenting the difference value of the photovoltaic power generation power in the current period and the photovoltaic power generation power in the last period; pPCCAnd the power absorbed by the light storage microgrid from the power grid in the last period of time is represented.
5. The energy management method of the light storage microgrid based on the real-time electricity price mechanism is characterized in that an energy storage system comprises n online energy storage converters, n is more than or equal to 1, the ith energy storage battery is connected to the ith online energy storage converter, i is 1, 2, … and n, and the outputs of the online energy storage converters are connected in parallel;
the upper limit value of the charging power of the energy storage system is
Figure FDA0002287746850000021
The lower limit value of the discharge power of the energy storage system is
Figure FDA0002287746850000022
Wherein, PPCS_ratedFor nominal power, U, of energy-storing convertersPCSi_DCThe dc voltage of the ith online energy storage converter,
Figure FDA0002287746850000023
the current is limited for charging the ith energy storage battery,
Figure FDA0002287746850000024
the maximum allowable charging power of the energy storage system is obtained;
Figure FDA0002287746850000025
the current is limited for the discharge of the ith energy storage cell,
Figure FDA0002287746850000026
the maximum allowable discharge power of the energy storage system.
6. The energy management method for the optical storage microgrid based on a real-time electricity price mechanism according to claim 1, wherein before the step of judging whether the electricity consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period, the method further comprises:
and judging that the increase rate or the decrease rate of the electricity purchasing price in the current time period exceeds a set threshold value.
7. The energy management method of the optical storage microgrid based on the real-time electricity price mechanism is characterized in that in the process of charging and discharging the energy storage system, the method further comprises the following steps:
detecting the SOC value of an energy storage battery in the energy storage system, and stopping the energy storage system from performing charging and discharging actions when the SOC is less than SOC1 or SOC is more than SOC 2; the SOC1 is the lower discharge limit of the energy storage system, and the SOC2 is the upper charge limit of the energy storage system.
8. The utility model provides an energy management system of light storage microgrid based on real-time electricity price mechanism which characterized in that includes:
the anti-reverse power transmission unit is used for judging whether the light storage micro-grid transmits power to the power grid reversely; if the condition of backward power transmission to the power grid occurs, closing each power conversion module in the light storage micro-grid;
the energy management unit is used for judging whether the power consumption cost of the energy storage system in the current time period is greater than the electricity purchase price in the current time period or not when the condition of backward power transmission to the power grid does not occur; if so, then: if the power absorbed by the light storage micro-grid from the power grid is enough to meet the local load power requirement, the local load power requirement is met preferentially, and the residual power is superposed with all the photovoltaic power generation power to charge the energy storage system; if the power requirement of the local load is not met, the superposed part of the photovoltaic power generation power preferentially meets the power requirement of the local load, and the photovoltaic residual power generation power charges the energy storage system; if not, then: the photovoltaic power generation power and the energy storage system discharge power supply the local load together, and the local load power requirement is met.
9. The energy management system of the optical storage microgrid based on a real-time electricity price mechanism is characterized in that the power absorbed by the optical storage microgrid from a power grid is equal to the effective capacity of a transformer in the optical storage microgrid.
10. The energy management system of the light-storage microgrid based on a real-time electricity price mechanism of claim 8, wherein the energy management unit is further configured to determine whether the electricity-consumption cost of the energy storage system in the current time period is greater than the electricity-purchasing price in the current time period, and before determining that the electricity-purchasing price increase rate or decrease rate in the current time period exceeds a set threshold.
CN201911167135.6A 2019-11-25 2019-11-25 Energy management method and system of light storage micro-grid based on real-time electricity price mechanism Pending CN110880759A (en)

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CN111864805A (en) * 2020-08-26 2020-10-30 合肥工业大学 Energy management method of industrial park micro-grid light storage combined power generation device
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CN111541256A (en) * 2020-05-18 2020-08-14 合肥阳光新能源科技有限公司 Energy control method and power generation and energy storage system
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