CN112260291B - Multi-mode economic operation method for AC/DC hybrid micro-grid based on incremental cost - Google Patents

Multi-mode economic operation method for AC/DC hybrid micro-grid based on incremental cost Download PDF

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CN112260291B
CN112260291B CN202011155821.4A CN202011155821A CN112260291B CN 112260291 B CN112260291 B CN 112260291B CN 202011155821 A CN202011155821 A CN 202011155821A CN 112260291 B CN112260291 B CN 112260291B
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CN112260291A (en
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杨帆
叶灵玥
李东东
林顺富
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Shanghai Electric Power University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/02—Circuit arrangements for ac mains or ac distribution networks using a single network for simultaneous distribution of power at different frequencies; using a single network for simultaneous distribution of ac power and of dc power
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P80/00—Climate change mitigation technologies for sector-wide applications
    • Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
    • Y02P80/14—District level solutions, i.e. local energy networks

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention provides an incremental cost-based multi-mode economic operation method of an AC/DC hybrid micro-grid, which is used for carrying out operation control on the AC/DC hybrid micro-grid comprising a plurality of sub-networks with different equivalent frequencies/voltages, and comprises the following steps: step 1, setting three operation modes of a sub-network, namely a sub-network power autonomous mode, an inter-network power sharing mode and a sub-network-energy storage power coordination mode; and 2, establishing an upper layer control structure and a lower layer control structure, solving the incremental cost of the controllable subsystems in the bottom layer control, adopting droop control based on the incremental cost for charging and discharging the sub-network power generation and energy storage system, balancing the incremental cost of each controllable subsystem, outputting a mode switching signal according to the local load condition of the sub-network, the incremental cost change, cost parameters of other sub-networks and input/output power of the sub-network by the upper layer control, switching between operation modes by taking the mode switching signal as the input signal of the bottom layer control, and adjusting the input/output power of the sub-network and the charging/discharging power of the energy storage system.

Description

Multi-mode economic operation method for AC/DC hybrid micro-grid based on incremental cost
Technical Field
The invention belongs to the field of coordination control of an alternating current-direct current hybrid micro-grid, and particularly relates to an incremental cost-based multi-mode economic operation method of an alternating current-direct current hybrid micro-grid.
Background
Because the output of the distributed power supply is largely provided with direct current characteristics, the direct current load is increased year by year, compared with a single micro-grid, the alternating current/direct current hybrid micro-grid not only can integrate micro-grids with different levels of frequency/voltage, but also can realize energy scheduling and mutual assistance among the sub-grids, and improve the reliability of mutual power supply, but because the power in the sub-grids is uninterruptedly interacted, a large amount of loss is easily caused, the energy storage system is frequently charged and discharged, the utilization rate of the distributed power supply is reduced, meanwhile, the running cost and the efficiency of each controllable sub-system in the system are different, and the traditional control can neglect the economical efficiency when distributing the power according to the capacity proportion of the sub-grid.
Disclosure of Invention
The invention aims to solve the problems, and aims to provide an incremental cost-based multi-mode economic operation method for an alternating current/direct current hybrid micro-grid.
The invention provides an incremental cost-based multi-mode economic operation method of an AC/DC hybrid micro-grid, which is used for carrying out operation control on the AC/DC hybrid micro-grid comprising a plurality of sub-networks with different level frequencies/voltages, and has the characteristics that the method comprises the following steps: step 1, setting three operation modes of a sub-network, namely a sub-network power autonomous mode, an inter-network power sharing mode and a sub-network-energy storage power coordination mode;
and 2, establishing an upper layer control structure and a lower layer control structure of an alternating current/direct current hybrid micro-grid, wherein the upper layer control structure comprises a bottom layer control and an upper layer control, in the bottom layer control, the incremental cost of each controllable subsystem is solved, the droop control based on the incremental cost is adopted for charging and discharging of the sub-grid power generation and energy storage system, the incremental cost of each controllable subsystem is balanced, the upper layer control is used for carrying out automatic switching between different operation modes according to the local load condition of the sub-grid, the incremental cost change and cost parameters of other sub-grids, and input/output power output mode switching signals of the energy storage system, when the sub-grid can maintain the local supply and demand balance, the sub-grid is in a sub-grid power autonomous mode, when larger power fluctuation occurs in the sub-grid, the sub-grid is switched to an inter-grid power sharing mode, when the system still can not maintain safe and stable operation, the sub-grid-energy storage power coordination mode is switched, the mode switching signal outputted by the upper layer control is used as an input signal of the bottom layer control, the input/output power of the sub-grid and the charge/discharge power of the energy storage system are adjusted, so that the alternating current/direct current hybrid micro-grid can operate in different operation modes simultaneously, and the energy storage system can be connected with an energy storage unit in parallel with the sub-grid in a plurality of energy storage units, and the energy storage units can be connected in parallel with the sub-grid through the energy storage system.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: when in the autonomous power mode of the sub-network, the input and output power of the sub-network is zero, the inter-network power interaction is not performed, the energy storage system is in a standby state, and the power balance relationship of the sub-network is as follows:
in the formula (1) and the formula (2), P ac,i 、P dc,j The generated energy of the ith alternating current sub-network and the jth direct current sub-network,for the load power of the corresponding subnetwork, +.>Is the maximum capacity of the corresponding subnetwork.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: when the power sharing mode is in the inter-network power sharing mode, the power sharing is realized by the sub-network with surplus or deficient power through the bidirectional converter, the energy storage system is still in a standby state, and at the moment, the power balance relationship of the sub-network is as follows:
the global power balance relationship is:
in the formula (3) and the formula (4),for the input or output power value of the corresponding sub-network, the prescribed power is positive when flowing into the sub-network,
in the formula (5), m and n represent that the AC/DC hybrid micro-grid comprises m AC sub-networks and n DC sub-networks, L ac,i 、L dc,j Representing the operation mode of the ith AC sub-network and the jth DC sub-network, when L ac,i When=0, the ac subnet i is in the subnet power autonomous mode, when L ac,i When=1, the ac subnet i is in the inter-network power sharing mode, when L dc,j When=0, the dc subnet j is in the subnet power autonomous mode, when L dc,j When=1, the dc subnet j is in the inter-network power sharing mode.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: when the energy storage system is in the energy storage power coordination mode, all the subnets are in a power sharing state, but still cannot maintain safe and stable operation of the system, the energy storage system operates at the moment, power support is provided for the system, and the global power balance relationship is as follows:
the charge and discharge constraints of the energy storage unit are as follows:
in the formula (6), l represents that the energy storage system comprises l energy storage units and P es,k Indicating the charge and discharge power of the kth energy storage unit, and the positive value is set when the discharge is regulated,
in the formula (7) of the present invention,is the upper limit and the lower limit of the charge and discharge power of the kth energy storage unit, and SOC es,k For the state of charge of the kth energy storage unit, < >>And the upper limit and the lower limit of the charge state are the safe operation of the energy storage unit.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: wherein, the bottom layer control in the step 2 comprises the following substeps:
step 2-1, an objective function of economic operation of the AC/DC hybrid micro-grid system is as follows:
and the cost function of the subnetwork or energy storage unit is represented by the following relation:
by constructing the Lagrangian function, when the incremental costs of the controllable subsystems are equal, the total power generation cost of the system is minimal, and the incremental cost is the first derivative of the cost function:
step 2-2, adopting incremental cost-based droop control on the sub-network and the energy storage unit, wherein the expression is as follows:
f i ＝f i max +(f i min -f i max )λ ac,i (13)
then, the increment cost among the output/input power balance controllable subsystems of the sub-network is utilized, and the frequency/voltage of the sub-network and the public bus are processed by per unit to represent the load condition and increment cost change in the sub-network:
the per unit value of the frequency/voltage of the subnet and the per unit value of the common bus voltage are input into a proportional-integral controller, so that the steady-state error is zero, and the output of the proportional-integral controller corresponds to the active power command of the input/output of the subnet:
in the formula (8), C ac,i (P ac,i )、C dc,j (P dc,j ) C as a power generation cost function of the corresponding subnet es,k (P es,k ) For the charge-discharge cost function of the corresponding energy storage unit,
in the formulas (9) to (11), a i 、a j 、a k B is the quadratic coefficient of the cost function i 、b j 、b k C is a coefficient of primary term i 、c j 、c k Is a constant term which is used to determine the degree of freedom,
in the formula (12), lambda ac,i 、λ dc,j 、λ es,k Representing the incremental costs of the corresponding sub-network and the corresponding energy storage unit respectively,
in the formulas (13) - (15), f i For the output frequency of the ith AC sub-network, f i min 、f i max Minimum and maximum operating frequencies allowed for the ac subnetwork; v (V) dc,j For the output voltage of the jth dc sub-network,minimum and maximum operating voltages allowed for the DC sub-network, V cb For common bus voltage, ">A minimum and maximum operating voltage allowed for the common bus,
in the formula (16), gamma is { f i ，V dc,j ，V cb [ gamma ] is the per unit value of gamma n Rated for gamma, gamma max 、γ min Respectively a maximum value and a minimum value of gamma,
in the formulas (17) - (18), k p 、k i Is the proportional-integral gain in the proportional-integral controller.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: wherein, the autonomous power mode of the sub-network is set as a mode I, the power sharing mode between networks is set as a mode II, the coordination mode of the sub-network and the energy storage power is set as a mode III,
in the step 2, when upper layer control is performed, according to local load condition of the sub-network, incremental cost change, cost parameters of other sub-networks and input/output power as mode switching criteria, corresponding output mode switching signals are comprehensively judged, and threshold values alpha, beta are introduced, wherein alpha comprises alpha i 、α j Respectively used for managing the ith alternating current sub-network and the jth direct current sub-networkSwitching of the subnetwork between the mode I and the mode II, wherein beta is used for managing the switching between the mode II and the mode III, and the relation of alpha and beta is as follows:
0＜α＜β＜1(19)。
the multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: wherein, when the mode I and the mode II are switched,
the switching from mode I to mode II only needs to meet the condition that the corresponding subnet frequency/voltage exceeds the set threshold value, and the event A i 、A j The representation is:
Event A j :|V′ dc,j |＞α j (20)
Event A i :|f i '|＞α i (21)
when the mode II is switched to the mode I, two conditions that the autonomous operation is kept after the subnet switching mode is met and the switching of the subnet operation mode cannot cause the switching of other subnets to the mode III are met, and events B are respectively designed i 、B j And C i 、C j ：
The mode switch signal between subnet mode I and mode II is expressed as:
L ac,j ＝A i ∪B i ∪C i (26)
L dc,j ＝A j ∪B j ∪C j (27)
the mode switching signal is input into the bottom layer control, and the input and output power of the subnet is as follows:
in the formulas (22) - (25),indicating the effect of a switching of a subnet from mode II to mode I on the subnet, +.>The effect of switching a subnet from mode ii to mode i on the overall system is shown as:
in the formula (26) and the formula (27), U is a logical OR.
The multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost provided by the invention can also have the following characteristics: wherein, when the switching between the mode II and the mode III is performed,
when the subnet is switched from the mode II to the mode III, the voltage of the public bus needs to exceed a set threshold value or the power sharing among subnets cannot maintain the power balance of the system, and the events D, E are respectively represented by:
Event D:|V′ cb |＞β (34)
and the event D, E is false at the same time when switching from mode III to mode II, the mode switching signal between mode II and mode III is expressed as:
L es,k ＝D∪E (36)
the mode switching signal is input into the bottom layer for control, and the charging and discharging power of the energy storage unit is as follows:
effects and effects of the invention
According to the incremental cost-based multi-mode economic operation method of the AC/DC hybrid micro-grid, which is related by the invention, because three operation modes are set for the sub-grid, and the mode switching is performed under the corresponding condition through the upper control and the bottom control, the mode switching can be performed according to the operation condition of the sub-grid, the unnecessary power interaction is reduced, and the utilization rate of a distributed power supply and the flexibility of a system are improved; because the droop control based on the incremental cost is adopted for the sub-network and the energy storage system, and the incremental cost of the sub-network and the energy storage system is properly balanced, the system can be maintained to operate in a stable range in different operation modes, and meanwhile, the operation cost of the system is optimized.
Drawings
FIG. 1 is a flow diagram of an incremental cost based AC/DC hybrid microgrid multi-mode economic operation method in an embodiment of the present invention;
FIG. 2 is a sub-grid power generation of an AC/DC hybrid micro-grid in an embodiment of the invention;
FIG. 3 illustrates the sub-grid input/output power of the AC/DC hybrid micro grid and the charging/discharging power of the energy storage system according to an embodiment of the present invention;
FIG. 4 is a graph showing the sub-network of an AC/DC hybrid micro-grid and the incremental cost of an energy storage system in an embodiment of the invention;
FIG. 5 is a graph comparing the power generation cost of the AC/DC hybrid microgrid multi-mode economical operation method based on incremental cost and the subnet capacity ratio method in an embodiment of the invention.
Detailed Description
In order to make the technical means and effects of the present invention easy to understand, the present invention will be specifically described with reference to the following examples and the accompanying drawings.
< example >
Fig. 1 is a flow chart of an incremental cost based ac-dc hybrid microgrid multi-mode economic operation method in an embodiment of the present invention.
As shown in fig. 1, the multi-mode economic operation method of the ac/dc hybrid micro-grid based on incremental cost according to the present embodiment is used for performing operation control on the ac/dc hybrid micro-grid including a plurality of sub-networks with different level frequencies/voltages, and includes the following steps:
the sub-network of the AC/DC hybrid micro-grid is connected with the energy storage system in parallel on the public bus through the bidirectional converter, the energy storage system is provided with a plurality of energy storage units, and the controllable sub-system comprises the sub-network and the energy storage units.
Step 1, three operation modes are set for the sub-network, namely a sub-network power autonomous mode, an inter-network power sharing mode and a sub-network-energy storage power coordination mode.
When in the autonomous power mode of the subnetwork, the input/output power of the subnetwork is zero, the power interaction between the subnetworks is not performed, the energy storage system is in a standby state, and the power balance relationship of the subnetwork is as follows:
in the formula (1) and the formula (2), P ac,i 、P dc,j The generated energy of the ith alternating current sub-network and the jth direct current sub-network,for the load power of the corresponding subnetwork, +.>Is the maximum capacity of the corresponding subnetwork.
When in the inter-network power sharing mode, the power surplus or deficient subnets realize power sharing through the bidirectional converter, the energy storage system is still in a standby state, and at the moment, the power balance relationship of the subnets is as follows:
the global power balance relationship is:
in the formula (3) and the formula (4),for the input or output power value of the corresponding sub-network, the prescribed power is positive when flowing into the sub-network,
in the formula (5), m and n represent that the AC/DC hybrid micro-grid comprises m AC sub-networks and n DC sub-networks, L ac,i 、L dc,j Represents the firstThe operation mode of the i AC sub-networks and the j DC sub-network is L ac,i When=0, the ac subnet i is in the subnet power autonomous mode, when L ac,i When=1, the ac subnet i is in the inter-network power sharing mode, when L dc,j When=0, the dc subnet j is in the subnet power autonomous mode, when L dc,j When=1, the dc subnet j is in the inter-network power sharing mode.
When in the subnet-energy storage power coordination mode, all subnets are in a power sharing state, but still cannot maintain safe and stable operation of the system, the energy storage system operates at the moment, power support is provided for the system, and the global power balance relationship is as follows:
the charge and discharge constraints of the energy storage unit are as follows:
in the formula (6), l represents that the energy storage system comprises l energy storage units and P es,k Indicating the charge and discharge power of the kth energy storage unit, and the positive value is set when the discharge is regulated,
in the formula (7) of the present invention,is the upper limit and the lower limit of the charge and discharge power of the kth energy storage unit, and SOC es,k For the state of charge of the kth energy storage unit, < >>And the upper limit and the lower limit of the charge state are the safe operation of the energy storage unit.
And 2, establishing an upper layer control structure and a lower layer control structure of the AC/DC hybrid micro-grid, wherein the upper layer control structure comprises a bottom layer control and an upper layer control, in the bottom layer control, the incremental cost of each controllable subsystem is solved, the droop control based on the incremental cost is adopted for charging and discharging of the sub-grid power generation and energy storage system, the incremental cost of each controllable subsystem is balanced, the upper layer control is used for automatically switching between different operation modes according to the local load condition of the sub-grid, the incremental cost change, cost parameters of other sub-grids and input/output power output mode switching signals, when the sub-grid can maintain the local supply and demand balance, the sub-grid is in a sub-grid power autonomous mode, when larger power fluctuation occurs in the sub-grid, the sub-grid is switched to an inter-grid power sharing mode, when all the sub-grid is still unable to maintain safe and stable operation, the sub-grid energy storage power coordination mode is switched, the mode switching signal output by the upper layer control is used as an input signal of the bottom layer control to automatically switch between different operation modes, and the input/output power of the sub-grid and the energy storage system are adjusted, so that the running cost of the AC/DC hybrid micro-grid is stable under different operation modes can be optimized.
The underlying control in step 2 includes the following sub-steps:
step 2-1, an objective function of economic operation of the AC/DC hybrid micro-grid system is as follows:
and the cost function of the subnetwork or energy storage unit is represented by the following relation:
by constructing the Lagrangian function, when the incremental costs of the controllable subsystems are equal, the total power generation cost of the system is minimal, and the incremental cost is the first derivative of the cost function:
step 2-2, adopting incremental cost-based droop control on the sub-network and the energy storage unit, wherein the expression is as follows:
f i ＝f i max +(f i min -f i max )λ ac,i (13)
then, the increment cost among the output/input power balance controllable subsystems of the sub-network is utilized, and the frequency/voltage of the sub-network and the public bus are processed by per unit to represent the load condition and increment cost change in the sub-network:
the per unit value of the frequency/voltage of the subnet and the per unit value of the common bus voltage are input into a proportional-integral controller, so that the steady-state error is zero, and the output of the proportional-integral controller corresponds to the active power command of the input/output of the subnet:
in the formula (8), C ac,i (P ac,i )、C dc,j (P dc,j ) Cost function for power generation for corresponding subnetworkNumber, C es,k (P es,k ) For the charge-discharge cost function of the corresponding energy storage unit,
in the formulas (9) to (11), a i 、a j 、a k B is the quadratic coefficient of the cost function i 、b j 、b k C is a coefficient of primary term i 、c j 、c k Is a constant term which is used to determine the degree of freedom,
in the formula (12), lambda ac,i 、λ dc,j 、λ es,k Representing the incremental costs of the corresponding sub-network and the corresponding energy storage unit respectively,
in the formulas (13) - (15), f i For the output frequency of the ith AC sub-network, f i min 、f i max Minimum and maximum operating frequencies allowed for the ac subnetwork; v (V) dc,j For the output voltage of the jth dc sub-network,minimum and maximum operating voltages allowed for the DC sub-network, V cb For common bus voltage, ">A minimum and maximum operating voltage allowed for the common bus,
in the formula (16), gamma is { f i ，V dc,j ，V cb [ gamma ] is the per unit value of gamma n Rated for gamma, gamma max 、γ min Respectively a maximum value and a minimum value of gamma,
in the formulas (17) - (18), k p 、k i Is the proportional-integral gain in the proportional-integral controller.
Setting the autonomous power mode of the sub-network as a mode I, setting the power sharing mode between networks as a mode II, setting the coordination mode of the sub-network and the energy storage power as a mode III,
in the step 2, when upper layer control is performed, according to local load condition of the sub-network, incremental cost change, cost parameters of other sub-networks and input/output power as mode switching criteria, comprehensively judging and then corresponding to output mode switching signals, and introducing a thresholdThe values of alpha, beta, alpha including alpha i 、α j The method is used for respectively managing the switching of the ith alternating current sub-network and the jth direct current sub-network between the mode I and the mode II, and the relation of beta and beta is as follows:
0＜α＜β＜1 (19)。
when the mode I and the mode II are switched,
the switching from mode I to mode II only needs to meet the condition that the corresponding subnet frequency/voltage exceeds the set threshold value, and the event A i 、A j The representation is:
Event A j :|V′ dc,j |＞α j (20)
Event A i :|f i '|＞α i (21)
when the mode II is switched to the mode I, two conditions that the autonomous operation is kept after the subnet switching mode is met and the switching of the subnet operation mode cannot cause the switching of other subnets to the mode III are met, and events B are respectively designed i 、B j And C i 、C j ：
The mode switch signal between subnet mode I and mode II is expressed as:
L ac,j ＝A i ∪B i ∪C i (26)
L dc,j ＝A j ∪B j ∪C j (27)
the mode switching signal is input into the bottom layer control, and the input and output power of the subnet is as follows:
in the formulas (22) - (25),representing subnet by mode
II the effect of switching to mode I on the subnet,the effect of switching a subnet from mode ii to mode i on the overall system is shown as:
in the formula (26) and the formula (27), U is a logical OR.
When switching between the mode II and the mode III is performed,
when the subnet is switched from the mode II to the mode III, the voltage of the public bus needs to exceed a set threshold value or the power sharing among subnets cannot maintain the power balance of the system, and the events D, E are respectively represented by:
Event D:|V′ cb |＞β (34)
and the event D, E is false at the same time when switching from mode III to mode II, the mode switching signal between mode II and mode III is expressed as:
L es,k ＝D∪E (36)
the mode switching signal is input into the bottom layer for control, and the charging and discharging power of the energy storage unit is as follows:
in the embodiment, the multi-mode economic operation method of the AC/DC hybrid micro-grid based on incremental cost is also applied to the AC/DC hybrid micro-grid comprising 1 AC sub-network, 2 DC sub-networks and 2 energy storage units,
the generating capacity of the sub-network in the AC/DC hybrid micro-grid is shown in fig. 2, the input/output power of the sub-network and the charging/discharging power of the energy storage system are shown in fig. 3, the incremental cost of the sub-network and the energy storage system is shown in fig. 4, the operation control is carried out by the AC/DC hybrid micro-grid multi-mode economic operation method based on the incremental cost, and in the system operation process, the switching sequence of the AC sub-network modes is as follows: the mode I-mode II-mode III-mode II, the mode switching sequence of the direct current sub-network 1 is as follows: the mode I-mode II-mode III-mode II-mode I, the mode switching sequence of the DC sub-network 2 is mode II-mode III-mode II, and the incremental cost-based AC/DC hybrid micro-grid multi-mode economic operation method can effectively complete the mode switching and maintain the frequency/voltage within a safe range through practical application.
In this embodiment, the incremental cost-based ac/dc hybrid micro-grid multi-mode economic operation method and the subnet capacity ratio-based method of the present invention are also compared to each other to obtain a total power generation cost, and fig. 5 is a graph comparing the incremental cost-based ac/dc hybrid micro-grid multi-mode economic operation method and the subnet capacity ratio-based method to each other in the embodiment of the present invention.
As shown in FIG. 5, the incremental cost-based AC/DC hybrid microgrid multi-mode economic operation method effectively reduces the total power generation cost of the system.
Effects and effects of the examples
According to the multi-mode economic operation method of the AC/DC hybrid micro-grid based on the incremental cost, because three operation modes are set for the sub-grid and mode switching is performed under the corresponding condition through upper control and bottom control, mode switching can be performed according to the operation condition of the sub-grid, unnecessary power interaction is reduced, and the utilization rate of a distributed power supply and the flexibility of a system are improved; because the droop control based on the incremental cost is adopted for the sub-network and the energy storage system, and the incremental cost of the sub-network and the energy storage system is properly balanced, the system can be maintained to operate in a stable range in different operation modes, and meanwhile, the operation cost of the system is optimized.
The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.

Claims (5)

1. An incremental cost-based multi-mode economic operation method for an ac/dc hybrid micro-grid, which is used for performing operation control on the ac/dc hybrid micro-grid comprising a plurality of sub-networks with different levels of frequency/voltage, is characterized by comprising the following steps:
step 1, three operation modes are set for the sub-network, namely a sub-network power autonomous mode, an inter-network power sharing mode and a sub-network-energy storage power coordination mode;
step 2, an upper and lower control structure of the AC/DC hybrid micro-grid is established, wherein the upper control structure comprises a bottom control and an upper control, in the bottom control, incremental cost of each controllable subsystem is solved, droop control based on the incremental cost is adopted for charging and discharging of the sub-grid power generation and energy storage system, the incremental cost of each controllable subsystem is balanced, the upper control is used for carrying out automatic switching between different operation modes according to local load conditions of the sub-grid, incremental cost change, cost parameters of other sub-grids and input/output power output mode switching signals, when the sub-grid can maintain local supply and demand balance, the sub-grid is in a sub-grid power autonomous mode, when larger power fluctuation occurs in the sub-grid, the sub-grid is switched to the inter-grid power sharing mode, when all the sub-grid is in the inter-grid power sharing mode, the system still can not maintain safe and stable operation, the sub-grid-energy storage power coordination mode is switched, the mode switching signals output by the upper control are used as input signals of the control to carry out automatic switching between different operation modes, the input/output power of the sub-grid and the charge/output power of the energy storage system are adjusted, the hybrid micro-grid is enabled to operate in the different operation modes and the stable operation modes,
wherein the subnetwork is connected with the energy storage system in parallel on a public bus through a bidirectional converter,
the energy storage system is provided with a plurality of energy storage units,
the controllable subsystem comprises the sub-network and the energy storage unit,
setting the autonomous power mode of the sub-network as a mode I, setting the inter-network power sharing mode as a mode II, setting the coordination mode of the sub-network and the energy storage power as a mode III,
in the step 2, when upper layer control is performed, according to local load condition of the sub-network, incremental cost change, cost parameters of other sub-networks and input/output power, which are taken as mode switching criteria, the mode switching signals are correspondingly output after comprehensive judgment, and threshold values alpha and beta are introduced, wherein alpha comprises alpha i 、α j The method is used for respectively managing the switching of the ith alternating current sub-network and the jth direct current sub-network between the mode I and the mode II, and the relation of beta and beta is as follows:
0＜α＜β＜1 (1)，
when the mode I and the mode II are switched,
the switching from mode I to mode II only needs to meet the condition that the corresponding subnet frequency/voltage exceeds the set threshold value, and the event A i 、A j The representation is:
Event A j :|V′ dc,j |＞α j (2)
Event A i :|f′ i |＞α i (3)
when the mode II is switched to the mode I, two conditions that the autonomous operation is kept after the subnet switching mode is met and the switching of the subnet operation mode cannot cause the switching of other subnets to the mode III are met, and events B are respectively designed i 、B j And C i 、C j ：
The mode switch signal between subnet mode i and mode ii is expressed as:
L ac,i ＝A i ∪B i ∪C i (8)
L dc,j ＝A j ∪B j ∪C j (9)
and inputting the mode switching signal into a bottom layer control, wherein the input and output power of the subnet is as follows:
k in formulas (10) - (11) p 、k i For the proportional-integral gain in the proportional-integral controller,
in the formulas (4) to (7),indicating the effect of a switching of a subnet from mode II to mode I on the subnet, +.>The effect of switching a subnet from mode ii to mode i on the overall system is shown as:
in the formulas (12) to (15), a i 、a j B is the quadratic coefficient of the cost function i 、b j For the coefficients of the primary term,
in the formula (8) and the formula (9), U is a logical OR,
when switching between the mode II and the mode III is performed,
when the subnet is switched from the mode II to the mode III, the voltage of the public bus needs to exceed a set threshold value or the power sharing among subnets cannot maintain the power balance of the system, and the events D, E are respectively represented by:
Event D:|V′ cb |＞β (16)
and the event D, E is false at the same time when switching from mode III to mode II, the mode switching signal between mode II and mode III is expressed as:
L es,k ＝D∪E (18)
inputting the mode switching signal into a bottom layer for control, wherein the charge and discharge power of the energy storage unit is as follows:
in the formula (19), V cb As a result of the common bus voltage,a is the minimum and maximum working voltage allowed by the public bus k Is a quadratic coefficient of the cost function.
2. The incremental cost-based ac/dc hybrid microgrid multi-mode economical operation method of claim 1, characterized by:
when in the autonomous power mode of the subnetwork, the input and output power of the subnetwork is zero, no inter-network power interaction is performed, the energy storage system is in a standby state, and at this time, the power balance relationship of the subnetwork is as follows:
in the formula (20) and the formula (21), P ac,i 、P dc,j The generated energy of the ith alternating current sub-network and the jth direct current sub-network,for the load power of the corresponding subnetwork, +.>Is the maximum capacity of the corresponding subnetwork.
3. The incremental cost-based ac/dc hybrid microgrid multi-mode economical operation method of claim 1, characterized by:
when the power sharing mode is in the inter-network power sharing mode, the power sharing of the sub-network with surplus or shortage of power is realized through the bidirectional converter, the energy storage system is still in a standby state, and at the moment, the power balance relationship of the sub-network is as follows:
the global power balance relationship is:
in the formula (22) and the formula (23),for the input or output power value of the corresponding sub-network, the prescribed power is positive when flowing into the sub-network,
in the formula (24), m and n represent that the ac/dc hybrid micro-grid comprises m ac subnets and n dc subnets, and L ac,i 、L dc,j Representing the operation mode of the ith AC sub-network and the jth DC sub-network, when L ac,i When=0, the ac subnet i is in the subnet power autonomous mode, when L ac,i When=1, the ac subnetwork i is in the inter-network power sharing mode, when L dc,j When=0, the dc subnet j is in the subnet power autonomous mode, when L dc,j When=1, the dc subnetwork j is in the inter-network power sharing mode.
4. The incremental cost-based ac/dc hybrid microgrid multi-mode economical operation method of claim 1, characterized by:
when in the subnet-energy storage power coordination mode, all subnets are in a power sharing state, but still cannot maintain safe and stable operation of the system, at the moment, the energy storage system operates to provide power support for the system, and at the moment, the global power balance relationship is as follows:
the charge and discharge constraints of the energy storage unit are as follows:
in the formula (25), l represents that the energy storage system comprises l energy storage units, P es,k Indicating the charge and discharge power of the kth energy storage unit, and the positive value is set when the discharge is regulated,
in the formula (26) of the present invention,is the upper limit and the lower limit of the charge and discharge power of the kth energy storage unit, and SOC es,k For the state of charge of the kth energy storage unit, < >>And the upper limit and the lower limit of the charge state are the safe operation of the energy storage unit.
5. The incremental cost-based ac/dc hybrid microgrid multi-mode economical operation method of claim 1, characterized by:
wherein, the bottom layer control in the step 2 comprises the following substeps:
step 2-1, an objective function of economic operation of the AC/DC hybrid micro-grid system is as follows:
and the cost function of the subnetwork or energy storage unit is represented by the following relation:
by constructing the Lagrangian function, when the incremental costs of the controllable subsystems are equal, the total power generation cost of the system is minimal, and the incremental cost is the first derivative of the cost function:
and 2-2, adopting incremental cost-based droop control on the sub-network and the energy storage unit, wherein the expression is as follows:
and then balancing the incremental cost among the controllable subsystems by utilizing the output/input power of the subnet, and representing the load condition and incremental cost change in the subnet by adopting per unit processing of the frequency/voltage of the subnet and the public bus:
the per unit value of the frequency/voltage of the subnet and the per unit value of the common bus voltage are input into a proportional-integral controller, so that the steady-state error is zero, and the output of the proportional-integral controller corresponds to the active power command of the input/output of the subnet:
in the formula (27), C ac,i (P ac,i )、C dc,j (P dc,j ) C as a power generation cost function of the corresponding subnet es,k (P es,k ) For the charge-discharge cost function of the corresponding energy storage unit,
in the formulas (28) to (30), a i 、a j 、a k B is the quadratic coefficient of the cost function i 、b j 、b k C is a coefficient of primary term i 、c j 、c k Is a constant term which is used to determine the degree of freedom,
in the formula (31), lambda ac,i 、λ dc,j 、λ es,k Representing the incremental costs of the corresponding sub-network and the corresponding energy storage unit respectively,
in the formulas (32) - (34), f i For the output frequency of the ith AC sub-network, f i min 、f i max Minimum and maximum operating frequencies allowed for the ac subnetwork; v (V) dc,j For the output voltage of the jth dc sub-network,minimum and maximum operating voltages allowed for the DC sub-network, V cb For common bus voltage, ">A minimum and maximum operating voltage allowed for the common bus,
in the formula (35), γ is { f i ，V dc,j ，V cb [ gamma ] is the per unit value of gamma n Rated for gamma, gamma max 、γ min Respectively a maximum value and a minimum value of gamma,
in the formulas (36) - (37), k p 、k i Is the proportional-integral gain in the proportional-integral controller.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105226632A (en) * 2015-10-30 2016-01-06 上海电力学院 A kind of multi-mode of DC micro power grid system switches control method for coordinating
CN105514966A (en) * 2016-01-21 2016-04-20 上海电力学院 Energy storage optimization and coordination control method for direct-current micro grid group
CN110265991A (en) * 2019-05-07 2019-09-20 上海电力学院 A kind of distributed and coordinated control method of direct-current grid
CN110323790A (en) * 2019-06-13 2019-10-11 上海电力学院 A kind of alternating current-direct current mixing micro-capacitance sensor group multi-mode control method for coordinating and device
CN111740426A (en) * 2020-06-30 2020-10-02 上海电力大学 Island alternating current-direct current hybrid micro-grid group power cooperative control method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105226632A (en) * 2015-10-30 2016-01-06 上海电力学院 A kind of multi-mode of DC micro power grid system switches control method for coordinating
CN105514966A (en) * 2016-01-21 2016-04-20 上海电力学院 Energy storage optimization and coordination control method for direct-current micro grid group
CN110265991A (en) * 2019-05-07 2019-09-20 上海电力学院 A kind of distributed and coordinated control method of direct-current grid
CN110323790A (en) * 2019-06-13 2019-10-11 上海电力学院 A kind of alternating current-direct current mixing micro-capacitance sensor group multi-mode control method for coordinating and device
CN111740426A (en) * 2020-06-30 2020-10-02 上海电力大学 Island alternating current-direct current hybrid micro-grid group power cooperative control method

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Cost-Based Droop Schemes for Economic Dispatch in Islanded Microgrids;Feixiong Chen等;《IEEE TRANSACTIONS ON SMART GRID》;第08卷(第01期);63-74 *
基于增量成本一致性的孤岛微电网分布式下垂控制;张朝霞 等;《可再生能源》;第38卷(第04期);517-523 *

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