CN114884115A - Alternating current-direct current hybrid micro-grid distributed secondary control method based on dynamic consistency - Google Patents

Alternating current-direct current hybrid micro-grid distributed secondary control method based on dynamic consistency Download PDF

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CN114884115A
CN114884115A CN202210552852.6A CN202210552852A CN114884115A CN 114884115 A CN114884115 A CN 114884115A CN 202210552852 A CN202210552852 A CN 202210552852A CN 114884115 A CN114884115 A CN 114884115A
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network
direct current
alternating current
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power
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郑涛
李鹏宇
杨畅
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Xian Jiaotong 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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Abstract

The invention provides an alternating current-direct current hybrid micro-grid distributed secondary control method based on dynamic consistency. The interconnected converters only depend on local information to cooperatively participate in secondary control, the direct current side information is used for realizing active power mutual aid between the alternating current micro-grids and the direct current micro-grids, and the alternating current side information is used for providing reactive power support for the alternating current sub-grids. And finally, completing the control targets of voltage and frequency recovery and power equalization of the whole-network distributed power supply under the cooperative control of the interconnected converters and the distributed power supply. The invention simplifies the communication network topological structure, optimizes the plug and play function, fully utilizes the residual capacity of the interconnected converters, strengthens the mutual supporting capacity of the subnetworks at two sides and improves the robustness of the AC/DC hybrid micro-grid system.

Description

Distributed secondary control method for alternating current-direct current hybrid micro-grid based on dynamic consistency
Technical Field
The invention relates to the technical field of control over an alternating current-direct current hybrid microgrid, in particular to a distributed secondary control method for the alternating current-direct current hybrid microgrid based on dynamic consistency.
Background
In modern power systems, the microgrid not only provides an energy interface for the distributed power supply, but also improves the reliability of the traditional power system in extreme environments. However, with the rapid development of new energy technologies and distributed power generation, the dc distributed power and the load ratio are gradually increased, and when the ac grid is connected, the current needs to be converted by the energy conversion device, which undoubtedly increases the cost and reduces the efficiency. The problems are solved by the appearance of the alternating current-direct current hybrid microgrid, the hybrid microgrid is composed of an alternating current subnet, a direct current subnet and interconnected converters for connecting the subnets on two sides, the advantages of the alternating current microgrid and the direct current microgrid are considered, meanwhile, the hybrid microgrid is suitable for more kinds of distributed power supplies and loads, the hybrid microgrid can be flexibly connected into a system, the link of electric energy conversion is reduced, and the power supply reliability and the economical efficiency of the microgrid are improved. However, the complex network structure has higher requirements on the control strategy, especially the coordination control between the interconnected converters and the distributed power supply.
Currently, a hierarchical control structure is mostly adopted for a microgrid control strategy: the control system comprises a primary control layer, a secondary control layer and a tertiary control layer. The primary control layer determines the output characteristics of a single distributed power supply, the secondary control layer is responsible for frequency, voltage recovery and power distribution, and the tertiary control layer is responsible for optimization control and economic operation. The implementation manner of the secondary control can be divided into centralized control, distributed control and distributed control. The distributed control is based on a decentralized thought, global variables are introduced into a control link through mutual communication among distributed power supplies, so that the system has high robustness, the plug and play function of the distributed power supplies can be met, and the distributed control becomes a mainstream implementation mode of a secondary control layer.
In recent years, a control strategy based on a distributed consistency algorithm becomes the key research of scholars, and a great deal of research work is carried out on a micro-grid with a single power supply mode. However, the research of applying the technology to the alternating current-direct current hybrid microgrid is not common, and the main difficulty lies in the selection of the control strategy of the interconnected converters and the determination of the communication topological structure between the alternating current and direct current subnets, and on the basis of meeting the control requirement of the single-side subnets, the voltage support and the power sharing between the subnets need to be considered. At present, foreign scholars, such as the Enrique Espina Gonz lez, use a distributed consistency algorithm in an alternating current-direct current hybrid micro-grid to improve the power sharing accuracy of a whole-grid distributed power supply, but the strategy requires a communication link between the distributed power supply and an interconnected converter, so that the communication network is complex, and communication delay and a large number of communication variables may cause stability problems. Furthermore, since interconnected converters normally have a large capacity redundancy, their reactive support capability to the ac sub-network is to be exploited.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a distributed secondary control method of an alternating current and direct current hybrid microgrid based on dynamic consistency, which solves the problems of supporting and recovering the voltage and frequency of the alternating current and direct current hybrid microgrid and realizes the power equalization of a full-network distributed power supply. The method is still feasible and effective under the special conditions of load fluctuation, communication failure and the like, meets the plug and play function of the distributed power supply, improves the robustness and the power supply reliability of the alternating current and direct current hybrid micro-grid system, and also improves the overall stability and the economic operation level of the system.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
the AC/DC hybrid micro-grid distributed secondary control method based on dynamic consistency introduces a dynamic consistency theory into secondary control of an AC/DC hybrid micro-grid system, an interconnection converter regulates power flow on two sides of an AC sub-grid and a DC sub-grid through local information to provide reactive support for the AC sub-grid, a distributed power supply performs secondary control through a sparse communication network, and the interconnection converter and the distributed power supply cooperatively control to realize power sharing of a whole-grid distributed power supply.
The alternating current-direct current hybrid micro-grid system consists of an alternating current sub-network, a direct current sub-network, an interconnection converter and a sparse communication network; the interconnection converter is connected with an alternating current sub-network and a direct current sub-network, an alternating current type distributed power supply and a load are connected inside the alternating current sub-network, and a direct current type distributed power supply and a load are connected inside the direct current sub-network; the sparse communication network is composed of secondary controllers of a whole-network distributed power supply, the interconnected converters do not participate in communication, nodes in the alternating current sub-network and the direct current sub-network are in adjacent communication, at least one communication link exists between the alternating current sub-network and the direct current sub-network, and the secondary controllers are responsible for collecting and sending local information and receiving adjacent node information.
The distributed secondary control method specifically comprises the following steps:
step 1), establishing an alternating current and direct current hybrid micro-grid system, and acquiring structural parameters of the alternating current and direct current hybrid micro-grid and rated parameters of each distributed power supply and an interconnection converter;
step 2), judging the proximity relation of each distributed power supply according to the structure of the alternating current-direct current hybrid micro-grid system, and determining the communication network structures of the adjacent distributed power supplies in the alternating current sub-network and the direct current sub-network and the communication relation of the distributed power supplies between the alternating current sub-network and the direct current sub-network;
and 3) determining an alternating current micro-source control mode according to the formula (1) and the formula (2), wherein the alternating current micro-source adopts a primary control strategy with droop characteristics to support the frequency and the voltage of an alternating current sub-network, and the distributed secondary control adjusts the state variable psi through the power information of the adjacent distributed power supplies i Hexix- i So as to realize the frequency and voltage recovery and power equalization of the AC sub-network; the power sharing specifically refers to that active power is distributed in the whole-network distributed power supply according to capacity, and reactive power is distributed in the alternating-current sub-network distributed power supply according to the proportion of the capacity;
Figure BDA0003655561310000041
Figure BDA0003655561310000042
in the formula, omega i And u i Respectively the output frequency of the ith AC micro sourceAnd an output voltage; omega ref And U ref Reference values of the output frequency and the output voltage respectively; n is a radical of an alkyl radical p And n q Respectively representing active-frequency and reactive-voltage droop control coefficients; p i * And
Figure BDA0003655561310000043
respectively representing the per unit values of the active power and the reactive power output by the ith alternating current micro source;
Figure BDA0003655561310000044
and
Figure BDA0003655561310000045
respectively representing reference values of active power and reactive power output by the ith alternating current micro source; psi i Hexix i Respectively representing state variables of active secondary control and reactive secondary control; tau. i And kappa i Control parameters for distributed secondary control; alpha is alpha i And beta i Frequency and voltage recovery coefficients, respectively; n is a radical of ac And N dc Respectively representing the total number of the AC micro sources and the DC micro sources of the whole network; a is ik And b ik Respectively representing communication coefficients of active secondary control and reactive secondary control; p k * And
Figure BDA0003655561310000046
the per unit value of active power and reactive power output by the kth distributed power supply obtained by communication is represented;
and 4) determining a direct current micro-source control mode according to the formula (3), wherein the direct current micro-source supports direct current voltage of a direct current sub-network by adopting a primary control strategy with droop characteristics, and the distributed secondary control regulates a state variable zeta through power information of adjacent distributed power supplies j So as to realize the direct voltage recovery and the power equipartition of the direct current sub-network; the power sharing specifically refers to that active power is proportionally distributed in the whole network distributed power supply according to the capacity of the power;
Figure BDA0003655561310000047
in the formula u dcj The output direct current voltage of the jth direct current micro source; u shape dcref To output a DC voltage reference; n is dc Representing an active-direct current voltage droop control coefficient;
Figure BDA0003655561310000051
expressing the unit value of the active power output by the jth direct current micro source;
Figure BDA0003655561310000052
the active power reference value of the jth direct current micro source output is represented; zeta j State variables representing active secondary control; oa (oa) j Control parameters for distributed secondary control; gamma ray j Restoring the coefficient for the direct current voltage; c. C jk A communication coefficient representing active secondary control; p k * Representing an active power per unit value output by the kth distributed power supply obtained by communication;
and 5), determining a control mode of the interconnected converter according to the formula (4), wherein the interconnected converter participates in active and reactive secondary control in a cooperative manner by depending on local alternating current and direct current information, and the specific content comprises the following steps: in active secondary control, a shaft d of the interconnected converter is controlled by constant direct-current voltage, the flow of active power between the alternating-current sub-network and the direct-current sub-network is regulated only by local information at a direct-current side, and when the alternating-current sub-network bears more loads, the interconnected converter transmits the active power from the direct-current sub-network to the alternating-current sub-network, and vice versa; in reactive secondary control, the interconnected converter adopts reactive-voltage droop control on a q axis, only depends on local information on an alternating current side to participate in reactive power support of the alternating current sub-network, when the voltage of the alternating current sub-network is reduced, the interconnected converter outputs reactive power to support alternating current voltage, otherwise, the interconnected converter absorbs the reactive power to reduce the alternating current voltage;
Figure BDA0003655561310000053
in the formula (I), the compound is shown in the specification,
Figure BDA0003655561310000054
the output voltage of the direct current side of the interconnected converter;
Figure BDA0003655561310000055
the rated voltage of the direct current side of the interconnected converter;
Figure BDA0003655561310000056
is a reactive output reference value of the interconnected converters;
Figure BDA0003655561310000057
the interconnected converters send out reactive power; n is ic Is the reactive support droop control coefficient;
Figure BDA0003655561310000058
is the mean value of the effective values of the alternating voltage;
Figure BDA0003655561310000059
is the rated voltage of the alternating current side of the interconnected converter.
Compared with the prior art, the invention has the following advantages:
1) on the basis of realizing the technical purpose, the communication network topological structure is simplified, the interconnection converter and the distributed power supply do not need to communicate, the plug and play function is optimized, the power supply reliability is improved, and the operation cost is reduced;
2) the interconnected converter participates in active and reactive secondary control at the same time, and also participates in reactive power regulation at the alternating current side while regulating the active power flow of the subnetworks at the two sides, so that the residual capacity of the interconnected converter is fully utilized, the mutual supporting capacity of the subnetworks at the two sides is enhanced, and the robustness of the alternating current-direct current hybrid microgrid system is improved.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a structure diagram of a communication network of an AC/DC hybrid micro-grid system;
FIG. 3 is a block diagram of a full network distributed power control;
FIG. 4 is a control block diagram of an interconnected inverter;
FIG. 5(a) is a graph of active power of a distributed power supply with varying AC load;
FIG. 5(b) is a graph of the active power of interconnected converters as the AC load changes;
fig. 6(a) is a graph of the active power of the distributed power source when the dc load changes;
FIG. 6(b) is a graph of the active power of the interconnected converters as the DC load changes;
FIG. 7(a) is a graph of reactive power of a distributed power supply as the reactive load changes;
FIG. 7(b) is a graph of the reactive power of the interconnected converters as the reactive load changes;
FIG. 8 is a power graph illustrating a single point communication failure;
fig. 9 is a power graph illustrating verification of plug and play functionality of a distributed power source.
Detailed Description
In order to make the technical scheme of the invention more clear and complete, the invention is described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The specific implementation case flow is shown as the attached figure 1, and the steps are as follows:
step 1), establishing an alternating current and direct current hybrid microgrid system, wherein the structure of the microgrid system is shown in the attached figure 2; and acquiring structural parameters of the alternating-current and direct-current hybrid micro-grid and rated parameters of the grid-connected converter, wherein the parameters are shown in table 1. As shown in fig. 2, the alternating current-direct current hybrid microgrid system comprises an alternating current sub-network, a direct current sub-network, an interconnection converter and a sparse communication network; the interconnection converter is connected with an alternating current sub-network and a direct current sub-network, an alternating current type distributed power supply and a load are connected inside the alternating current sub-network, and a direct current type distributed power supply and a load are connected inside the direct current sub-network; the sparse communication network is composed of secondary controllers of a whole-network distributed power supply, the interconnected converters do not participate in communication, nodes in the alternating current sub-network and the direct current sub-network are in adjacent communication, at least one communication link exists between the alternating current sub-network and the direct current sub-network, and the secondary controllers are responsible for collecting and sending local information and receiving adjacent node information.
TABLE 1 microgrid architecture parameters
Figure BDA0003655561310000071
And 2) judging the proximity relation of each distributed power supply according to the structure of the alternating current-direct current hybrid micro-grid system, and determining the communication network structures of the adjacent distributed power supplies in the alternating current sub-network and the direct current sub-network and the communication relation of the distributed power supplies between the alternating current sub-network and the direct current sub-network, wherein the topological structure of the communication network is shown in the attached figure 2.
And 3) determining an alternating current micro-source control mode according to the formula (1) and the formula (2), wherein a control block diagram is shown in the attached figure 3. The alternating current micro source supports alternating current sub-network frequency and voltage by adopting a primary control strategy with droop characteristics, and distributed secondary control adjusts a state variable psi through power information of adjacent distributed power supplies i Hexix- i So as to realize the frequency and voltage recovery and power equalization of the AC sub-network; the power sharing specifically refers to that active power is distributed in the whole-network distributed power supply according to capacity, and reactive power is distributed in the alternating-current sub-network distributed power supply according to the proportion of the capacity;
Figure BDA0003655561310000081
Figure BDA0003655561310000082
in the formula, ω i And u i The output frequency and the output voltage of the ith alternating current micro source are respectively; omega ref And U ref Reference values of the output frequency and the output voltage respectively; n is p And n q Respectively representing active-frequency and reactive-voltage droop control coefficients; p i * And
Figure BDA0003655561310000083
respectively representing the per unit values of the active power and the reactive power output by the ith alternating current micro source;
Figure BDA0003655561310000084
and
Figure BDA0003655561310000085
respectively representing the reference values of the active power and the reactive power output by the ith alternating current micro source; psi i Hexix- i Respectively representing state variables of active secondary control and reactive secondary control; tau is i And kappa i Control parameters for distributed secondary control; alpha is alpha i And beta i Frequency and voltage recovery coefficients, respectively; n is a radical of ac And N dc Respectively representing the total number of the AC micro sources and the DC micro sources of the whole network; a is ik And b ik Respectively representing communication coefficients of active secondary control and reactive secondary control; p k * And
Figure BDA0003655561310000086
the per unit value of active power and reactive power output by the kth distributed power supply obtained by communication is represented; the control parameters are shown in table 2.
Table 2 microgrid control parameters
Figure BDA0003655561310000087
Figure BDA0003655561310000091
And 4) determining a direct current micro-source control mode according to the formula (3), wherein a control block diagram is shown in figure 3. The direct current micro source supports direct current voltage of a direct current sub-network by adopting a primary control strategy with droop characteristics, and distributed secondary control regulates a state variable zeta through power information of adjacent distributed power supplies j So as to realize the direct voltage recovery and the power equipartition of the direct current sub-network; wherein the power sharing means active powerThe rate is proportionally distributed in the whole network distributed power supply according to the capacity of the power supply;
Figure BDA0003655561310000092
in the formula u dcj The output direct current voltage of the jth direct current micro source; u shape dcref To output a DC voltage reference; n is dc Representing an active-direct current voltage droop control coefficient;
Figure BDA0003655561310000093
expressing the unit value of the active power output by the jth direct current micro source;
Figure BDA0003655561310000094
the active power reference value of the jth direct current micro source output is represented; zeta j State variables representing active secondary control; oa j Control parameters for distributed secondary control; gamma ray j Restoring the coefficient for the direct current voltage; c. C jk A communication coefficient representing active secondary control; p k * Representing an active power per unit value output by the kth distributed power supply obtained by communication; the control parameters are shown in table 2.
And 5) determining the control mode of the interconnected converter according to the formula (4), wherein the control block diagram is shown in the attached figure 4. The interconnected converter respectively depends on local alternating current and direct current information to cooperatively participate in active and reactive secondary control, and the interconnected converter specifically comprises the following contents: in active secondary control, a shaft d of the interconnected converter is controlled by constant direct-current voltage, the flow of active power between the alternating-current sub-network and the direct-current sub-network is regulated only by local information at a direct-current side, and when the alternating-current sub-network bears more loads, the interconnected converter transmits the active power from the direct-current sub-network to the alternating-current sub-network, and vice versa; in reactive secondary control, the interconnected converter adopts reactive-voltage droop control on a q axis, only depends on local information on an alternating current side to participate in reactive power support of the alternating current sub-network, when the voltage of the alternating current sub-network is reduced, the interconnected converter outputs reactive power to support alternating current voltage, otherwise, the interconnected converter absorbs the reactive power to reduce the alternating current voltage;
Figure BDA0003655561310000101
in the formula (I), the compound is shown in the specification,
Figure BDA0003655561310000102
the output voltage of the direct current side of the interconnected converter;
Figure BDA0003655561310000103
the rated voltage of the direct current side of the interconnected converter;
Figure BDA0003655561310000104
is a reactive output reference value of the interconnected converters;
Figure BDA0003655561310000105
the interconnected converters send out reactive power; n is a radical of an alkyl radical ic Is the reactive support droop control coefficient;
Figure BDA0003655561310000106
is the mean value of the effective values of the alternating voltage;
Figure BDA0003655561310000107
is the rated voltage of the alternating current side of the interconnected converter. The control parameters are shown in table 2.
The implementation case verifies the feasibility of the control strategy under different working conditions:
fig. 5(a) is a graph of the active power of the distributed power source when the ac load changes, and fig. 5(b) is a graph of the active power of the interconnected converters when the ac load changes. As can be seen from the figure, after the control strategy is adopted, the active power equalization is realized by the three distributed power supplies, and the power equalization state can be quickly coordinated and recovered when the load on the subsequent alternating current side is increased and reduced. The interconnected converter can dynamically adjust active power along with the load according to local information, and specifically shows that when the alternating current load is increased, the transmission power of the direct current side is increased, or the transmission power of the alternating current side is reduced, or vice versa, so that the distributed power supply is assisted to finish power sharing.
Fig. 6(a) is a graph of the active power of the distributed power source when the dc load changes, and fig. 6(b) is a graph of the active power of the interconnected converters when the dc load changes. It can be seen from the figure that the control strategy of the present invention can still ensure that the distributed power supply is in a power sharing state when the dc load is increased or decreased. Different from the alternating current load change, the interconnected converter uses constant direct current voltage control in the process and depends on direct current side information, so that the power supporting action of the interconnected converter is faster when the direct current load changes, the power supporting action can still be kept stable in subsequent control, and the active power is dynamically adjusted along with the load.
Fig. 7(a) is a reactive power curve of the distributed power source when the reactive load changes, and fig. 7(b) is a reactive power curve of the interconnected converters when the reactive load changes. As can be seen, this strategy still ensures that the ac micro-source maintains a uniform reactive power distribution as the reactive load increases or decreases. In addition, the interconnected converter can also dynamically adjust the reactive power according to the local alternating current side information, and the method is specifically characterized in that when the voltage is reduced due to the increase of the reactive load on the alternating current side, the interconnected converter outputs the reactive power to support the alternating current voltage, and vice versa.
Fig. 8 is a power curve diagram when a single-point communication failure fault occurs, and it can be seen from the diagram that, by using the control strategy of the present invention, after three distributed power sources complete power equalization, the DG2 is cut off to simulate a communication failure fault, and then the load is increased, so that the remaining two distributed power sources can still realize a power equalization state, and the DG2 can only maintain droop control once due to no information interaction, but can still continue to participate in power equalization after subsequent communication is restored. This embodiment illustrates that a small area communication failure does not affect the stability of the control system.
Fig. 9 is a plug and play power curve diagram of the distributed power supplies, and it can be seen from the graph that when t is 10s, DG2 is cut off and communication is disconnected, and the remaining two distributed power supplies can still keep power equally divided; when t is 35s, the DG2 is merged, and the output power is controlled by only depending on the droop; when t is 45s, DG2 accesses the communication network to achieve power sharing. The implementation case embodies that the control strategy of the invention can meet the plug and play function of the distributed power supply, the input and the removal are more flexible, the stability of the system can be ensured in the process, and the invention has better power supply reliability and system robustness.
The technical solutions of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the scope of the present invention. On the basis of the technical scheme of the invention, various modifications or changes which can be made by a person skilled in the art without creative efforts are still within the protection scope of the invention.

Claims (3)

1. An alternating current-direct current hybrid micro-grid distributed secondary control method based on dynamic consistency is characterized in that: the dynamic consistency theory is introduced into secondary control of the alternating current-direct current hybrid micro-grid system, the interconnection converter regulates power flow on two sides of the alternating current sub-grid and the direct current sub-grid through local information, reactive power support is provided for the alternating current sub-grid, the distributed power supply is subjected to secondary control through the sparse communication network, and the interconnection converter and the distributed power supply are cooperatively controlled to achieve power sharing of the whole-grid distributed power supply.
2. The alternating current-direct current hybrid microgrid distributed secondary control method based on dynamic consistency of claim 1 is characterized in that: the alternating current-direct current hybrid micro-grid system consists of an alternating current sub-network, a direct current sub-network, an interconnection converter and a sparse communication network; the interconnection converter is connected with an alternating current sub-network and a direct current sub-network, an alternating current type distributed power supply and a load are connected inside the alternating current sub-network, and a direct current type distributed power supply and a load are connected inside the direct current sub-network; the sparse communication network is composed of secondary controllers of a whole-network distributed power supply, the interconnected converters do not participate in communication, nodes in the alternating current sub-network and the direct current sub-network are in adjacent communication, at least one communication link exists between the alternating current sub-network and the direct current sub-network, and the secondary controllers are responsible for collecting and sending local information and receiving adjacent node information.
3. The method for distributed quadratic control based on the hybrid AC/DC microgrid of claim 1, characterized in that the method comprises the following steps:
step 1), establishing an alternating current and direct current hybrid micro-grid system, and acquiring structural parameters of the alternating current and direct current hybrid micro-grid and rated parameters of each distributed power supply and an interconnection converter;
step 2), judging the proximity relation of each distributed power supply according to the structure of the alternating current-direct current hybrid micro-grid system, and determining the communication network structures of the adjacent distributed power supplies in the alternating current sub-network and the direct current sub-network and the communication relation of the distributed power supplies between the alternating current sub-network and the direct current sub-network;
and 3) determining an alternating current micro-source control mode according to the formula (1) and the formula (2), wherein the alternating current micro-source adopts a primary control strategy with droop characteristics to support the frequency and the voltage of an alternating current sub-network, and the distributed secondary control adjusts the state variable psi through the power information of the adjacent distributed power supplies i Hexix- i So as to realize the frequency and voltage recovery and power equalization of the AC sub-network; the power sharing specifically refers to that active power is distributed in the whole-network distributed power supply according to capacity, and reactive power is distributed in the alternating-current sub-network distributed power supply according to the proportion of the capacity;
Figure FDA0003655561300000021
Figure FDA0003655561300000022
in the formula, ω i And u i The output frequency and the output voltage of the ith alternating current micro source are respectively; omega ref And U ref Reference values of the output frequency and the output voltage respectively; n is p And n q Respectively representing active-frequency and reactive-voltage droop control coefficients; p i * And
Figure FDA0003655561300000023
respectively representing the per unit value of the i-th AC micro source to output active power and reactive power；
Figure FDA0003655561300000024
And
Figure FDA0003655561300000025
respectively representing the reference values of the active power and the reactive power output by the ith alternating current micro source; psi i Hexix- i Respectively representing state variables of active secondary control and reactive secondary control; tau is i And kappa i Control parameters for distributed secondary control; alpha is alpha i And beta i Frequency and voltage recovery coefficients, respectively; n is a radical of ac And N dc Respectively representing the total number of the AC micro sources and the DC micro sources of the whole network; a is ik And b ik Respectively representing communication coefficients of active secondary control and reactive secondary control; p k * And
Figure FDA0003655561300000026
the per unit value of active power and reactive power output by the kth distributed power supply obtained by communication is represented;
and 4) determining a direct current micro-source control mode according to the formula (3), wherein the direct current micro-source supports direct current voltage of a direct current sub-network by adopting a primary control strategy with droop characteristics, and the distributed secondary control regulates a state variable zeta through power information of adjacent distributed power supplies j So as to realize the direct voltage recovery and the power equipartition of the direct current sub-network; the power sharing specifically refers to that active power is proportionally distributed in the whole network distributed power supply according to the capacity of the power;
Figure FDA0003655561300000031
in the formula u dcj The output direct current voltage of the jth direct current micro source; u shape dcref To output a DC voltage reference; n is dc Representing an active-direct current voltage droop control coefficient;
Figure FDA0003655561300000032
expressing the unit value of the active power output by the jth direct current micro source;
Figure FDA0003655561300000033
the active power reference value of the jth direct current micro source output is represented; zeta j State variables representing active secondary control; oa j Control parameters for distributed secondary control; gamma ray j Restoring the coefficient for the direct current voltage; c. C jk A communication coefficient representing active secondary control; p k * Representing an active power per unit value output by the kth distributed power supply obtained by communication;
and 5), determining a control mode of the interconnected converter according to the formula (4), wherein the interconnected converter participates in active and reactive secondary control in a cooperative manner by depending on local alternating current and direct current information, and the specific content comprises the following steps: in active secondary control, a shaft d of the interconnected converter is controlled by constant direct-current voltage, the flow of active power between the alternating-current sub-network and the direct-current sub-network is regulated only by local information at a direct-current side, and when the alternating-current sub-network bears more loads, the interconnected converter transmits the active power from the direct-current sub-network to the alternating-current sub-network, and vice versa; in reactive secondary control, the interconnected converter adopts reactive-voltage droop control on a q axis, only depends on local information on an alternating current side to participate in reactive power support of the alternating current sub-network, when the voltage of the alternating current sub-network is reduced, the interconnected converter outputs reactive power to support alternating current voltage, otherwise, the interconnected converter absorbs the reactive power to reduce the alternating current voltage;
Figure FDA0003655561300000034
in the formula (I), the compound is shown in the specification,
Figure FDA0003655561300000035
the output voltage of the direct current side of the interconnected converter;
Figure FDA0003655561300000036
the rated voltage of the direct current side of the interconnected converter;
Figure FDA0003655561300000037
is a reactive output reference value of the interconnected converters;
Figure FDA0003655561300000038
the interconnected converters send out reactive power; n is ic Is the reactive support droop control coefficient;
Figure FDA0003655561300000039
is the mean value of the effective values of the alternating voltage;
Figure FDA00036555613000000310
is the rated voltage of the alternating current side of the interconnected converter.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116247734A (en) * 2023-05-11 2023-06-09 南方电网数字电网研究院有限公司 Distributed consistency power control method for edge-side weak communication environment
CN116247734B (en) * 2023-05-11 2024-03-12 南方电网数字电网研究院股份有限公司 Distributed consistency power control method for edge-side weak communication environment

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