CN115276038A - Distributed alternating current micro-grid frequency recovery method and system - Google Patents
Distributed alternating current micro-grid frequency recovery method and system Download PDFInfo
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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
- H02J3/241—The oscillation concerning frequency
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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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
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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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00004—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by the power network being locally controlled
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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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—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
- H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
Abstract
The invention discloses a distributed alternating current micro-grid frequency recovery method and a distributed alternating current micro-grid frequency recovery system, which relate to the technical field of power generation control and specifically comprise the following steps: collecting three-phase voltage information, current information, droop controller output angular frequency information and voltage, current and angular frequency information of a neighbor distributed power generation unit connected with a directional communication topology; calculating a distributed error index according to the acquired information; judging whether the local distributed power generation unit is attacked or not; if yes, each distributed power generation unit solves local distributed optimal auxiliary control input based on a system equation and an integral performance index equation of the distributed power generation unit; calculating an optimal angular frequency reference value; the invention adopts a complete distribution type, each DG has a distributed performance index belonging to the DG, global information is not needed, information is exchanged with adjacent DGs only based on a sparse communication network, consensus is achieved in a cooperation mode, and the requirement on a centralized performance index is eliminated.
Description
Technical Field
The invention relates to the technical field of power generation control, in particular to a distributed alternating current micro-grid frequency recovery method and system.
Background
With the massive access of distributed energy and the deep application of information technology in the smart grid, the information flow and the energy flow in the active power distribution network are deeply merged, so that the information flow becomes a typical information physical system (CPS). Due to the fact that CPS marketing behaviors of the active power distribution network are gradually widened, interaction between users and the power distribution network is increasingly frequent, and the active power distribution network faces a severe challenge in terms of dealing with information safety risks. The ac microgrid is a component of an active power distribution network CPS, which is connected to a main network in the form of an autonomous system via a Point of Common Coupling (PCC). When the micro-grid operates in a grid-connected mode, the voltage support and the frequency synchronization of the micro-grid are strictly controlled by the main grid. When the grid fails, the microgrid will quickly switch to island mode operation. Due to the loss of the support of the voltage and the frequency of the power grid, the power grid must be autonomous by a control system to realize the synchronization of the voltage and the frequency.
Conventional microgrid systems are typically controlled using a hierarchical control architecture. The main control is realized locally in the power supply unit, the operation is carried out under a rapid time scale, only difference adjustment can be carried out, the difference adjustment is used for balancing the generated energy and the load demand of the microgrid, and droop control is generally adopted. The quadratic control operates on a medium time scale to compensate for voltage and frequency deviations generated by the main control in case of mode switching or failure. And the third control is operated under a longer time scale, and the micro-grid is controlled to operate under a better economic condition according to the flow between the micro-grid and the main grid. The secondary control ensures that the micro-grid operates under a nominal condition, and plays a vital role in improving the electric energy quality of a user side or a load side.
Centralized control relies on a central controller (MGCC) and a highly interconnected communication network, and the control system is robust. However, the scalability, flexibility and reconfigurability of the centralized control system are poor, and plug and play cannot be realized. When the MGCC is attacked by malicious information, the overall paralysis of the micro-grid can be caused. The distributed control does not need a communication system, can greatly reduce the complexity of the system and has higher convergence speed. However, the control method cannot optimize the output of each unit generally, and it is difficult to realize consistent coordination of distributed generation units (DG). Therefore, how to guarantee consistent cooperation of DGs by using a sparse communication network is an urgent problem to be solved by those skilled in the art.
Disclosure of Invention
In view of this, the present invention provides a distributed ac microgrid frequency recovery method and system, which overcome the above-mentioned drawbacks.
In order to achieve the above purpose, the invention provides the following technical scheme:
a frequency recovery method based on a distributed alternating current micro-grid comprises the following specific steps:
collecting three-phase voltage information v of local alternating current microgrid bus oi And three-phase current information i oi Local droop controller outputting angular frequency information omega i And the voltage v of the neighboring distributed generation units connected to the communication topology oj Current i oj Angular frequency information omega j ；
According to the three-phase voltage information v of the local AC micro-grid bus oi Three-phase current information i oi Local droop controller outputting angular frequency information omega i And the voltage v of the neighboring distributed generation units connected to the communication topology oj Current i oj Angular frequency information omega j Calculating a distributed error index e i ；
According to a distributed error index e i Judging the attack condition of the local distributed power generation unit;
if any distributed power generation unit is attacked, each distributed power generation unit collaboratively solves local distributed optimal auxiliary control input based on the system equation and integral performance index of each distributed power generation unit
Based on locally distributed optimal auxiliary control input
Calculating an optimal angular frequency reference value
Optionally, the distributed error index e of any distributed power generation unit i The calculation formula of (2) is as follows:
in the formula, a i,j Is an element of the adjacency matrix; omega i Outputting angular frequency information for a local droop controller; omega j Angular frequency information for adjacent distributed power generation units; y is i Outputting a value for the local system; omega ref Is a reference voltage; b i Connecting elements of the gain matrix for the reference values; j is a neighbor node.
Optionally, the system equation of any distributed power generation unit is:
in the formula (I), the compound is shown in the specification,
is the first derivative of the system state; x is the number of i Is the local system state; y is i Outputting a value for the local system; u. of i A local auxiliary control input; i is a local node; A. b and C are both system matrixes.
Optionally, a local auxiliary control input u i The expression of (a) is:
in the formula, R is a positive definite constant matrix; r is i Is a positive scalar quantity; i is a local node; b is a system matrix; x is the number of n Is a state variable of the nth distributed generation unit; p i,n Lambda is a multiplier of Langerday i A matrix of coefficients related to the state variables; xi i Is a lambd of a lambertian multiplier i A matrix of coefficients independent of the state variables.
Optional, locally distributed optimal auxiliary control input
The acquisition steps are as follows:
constructing a system equation and an integral performance index equation of any distributed power generation unit, and constructing an integral performance index J i The expression of (c) is:
in the formula, e i Is a local error index; u. of i A local auxiliary control input; q. q.s i 、r i Are all positive scalars; q and R are both positive definite constant matrixes;
introducing lagrange multiplier lambda i Obtaining local auxiliary control input u based on system equation and integral performance index equation of each distributed power generation unit i The expression of (2);
for lagrange multiplier lambda i System equation and integral performance index equation of each distributed power generation unit and auxiliary control input u i The expression of (2) is subjected to multiple combined operations to obtain an optimal state track;
computing local distributed optimal auxiliary control inputs based on optimal state trajectories
Optionally, any optimum angular frequency reference value
The calculation formula of (2) is as follows:
in the formula u i A local auxiliary control input; d P,i Is a droop control coefficient; p is i The output active power for the local VSI.
A frequency recovery system based on a distributed alternating current micro-grid comprises a communication network, a state collector, an attack detection module, a distributed optimal cooperative controller, a power controller, a voltage controller, a current controller and a voltage source type inverter;
a communication network for transmission of data;
a state collector for collecting three-phase voltage information v of local AC microgrid bus oi Three-phase current information i oi Local droop controller outputting angular frequency information omega i And the voltage v of the adjacent distributed generation unit of any one of the distributed generation units oj Current i oj Angular frequency information omega j ；
An attack detection step, which is used for judging whether each distributed power generation unit is attacked or not and sending a control signal to the distributed optimal cooperative controller;
distributed optimal cooperative controller for computing local distributed optimal auxiliary control input
And an optimum angular frequency reference value
A power controller for controlling the power according to the optimal angular frequency reference value
Completing the compensation of the frequency deviation;
voltage controller ofAccording to a reference voltage
Deriving a reference current for an input current controller
A current controller for controlling the current according to the reference current
Obtaining a reference voltage for controlling a PWM generator to generate a PWM signal according to the output current of the voltage source type inverter;
voltage source type inverter for controlling angular frequency omega according to PWM signal and power controller i And outputting the voltage.
Optionally, the system is divided into a physical layer and an information layer;
the physical layer comprises n distributed power generation units, and the n distributed power generation units are connected to a local microgrid bus through a voltage source type inverter;
the information layer is a directed connection communication topology containing a spanning tree.
Optionally, the directional connection communication topology is represented by G (V, E, a, B), where V is a node set; e is a directed edge set; a is an adjacency matrix of the topology; b is the connection gain matrix.
Optionally, the microgrid comprises n distributed power generation units and m integrated loads.
According to the technical scheme, the invention discloses a distributed AC micro-grid frequency recovery method and a distributed AC micro-grid frequency recovery system, and compared with the prior art, the distributed AC micro-grid frequency recovery method and the distributed AC micro-grid frequency recovery system have the following advantages:
1. the invention adopts complete distribution, each DG has the own distributed performance index, global information is not needed, information is exchanged with the adjacent DGs only on the basis of a sparse communication network, consensus is achieved in a cooperation mode, and the requirement on the centralized performance index is eliminated;
2. the invention has universality to different communication topologies;
3. the method provided by the invention can realize the optimal frequency consistency recovery of each distributed generator set under the attack of the microgrid by using the minimum control energy, and the convergence speed is accelerated by considering the synchronism among the generator sets.
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 embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of the structure of the information layer and the physical layer of the present invention;
FIG. 2 is a schematic diagram of a four-unit two-integrated-load microgrid topology structure according to the present invention;
FIG. 3 is a schematic diagram of the communication network topology of FIG. 2;
FIG. 4 is a schematic diagram of a single distributed generation unit local control system configuration of the present invention;
FIG. 5 is a schematic flow chart of the method 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 obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The embodiment of the invention discloses a distributed alternating current microgrid frequency recovery system, which is divided into a physical layer and an information layer as shown in figure 1;
and in the physical layer, the n distributed generation units are connected to the microgrid bus through Voltage Source Inverters (VSIs). And circuit equivalent impedance is formed between the buses.
And the information layer comprises a sparse and efficient directed connection communication topology of the spanning tree. The directed connectivity topology can be represented by G (V, E, A, B); wherein V = { V = 1 ,v 2 ,...,v n The is a node set; e is a directed edge set; n is a radical of hydrogen i Representing a set of neighbor nodes, N i ＝{v j |(i,j)∈E}；
Is a contiguous matrix of the topology, A = [ a = [) i,j ]Wherein a is i,j When the directional communication is carried out, the value is 1, otherwise, the value is 0;
to connect the gain matrix, wherein b if node i can receive the information of the leader node i The value is 1, otherwise 0. The sparse and efficient communication network involved in the embodiment is a directed connectivity topology including a spanning tree, and meets the condition of inducing multi-MAS cooperation consensus.
The graph Laplace matrix of the communication topology is
The microgrid in this embodiment is composed of n distributed power generation units and m integrated loads, as shown in fig. 2, the microgrid is a microgrid with four units and two integrated loads, and the communication topology of the microgrid may be six or more than six in fig. 3, as shown in fig. 3.
For the inside of each distributed power generation unit, a block diagram of frequency recovery optimal distributed cooperative control under malicious attack is shown in fig. 4, and comprises a communication network, a state collector, an attack detection module, a distributed optimal cooperative controller, a power controller, a voltage controller, a current controller and a voltage source type inverter;
a communication network for transmission of data; a state collector for collecting three-phase voltage information v of local AC microgrid bus oi Three-phase current information i oi Local droop controller output angular frequency information omega i And the voltage v of the adjacent distributed generation unit of any one of the distributed generation units oj Current i oj Angular frequency information omega j (ii) a An attack detection step, which is used for judging whether each distributed power generation unit is attacked or not and sending a control signal to the distributed optimal cooperative controller; distributed optimal cooperative controller for computing local distributed optimal auxiliary control input
And an optimum angular frequency reference value
A power controller for controlling the power according to the optimal angular frequency reference value
Completing the compensation of the frequency deviation; a voltage controller for controlling the voltage according to the reference voltage
Deriving a reference current for an input current controller
A current controller for controlling the current according to the reference current
Obtaining a reference voltage for controlling a PWM generator to generate a PWM signal according to the output current of the voltage source type inverter; voltage source type inverter for controlling angular frequency omega of power controller according to PWM signal i And outputting the voltage.
In another embodiment, a state estimator is further included for estimating states of neighboring nodes.
The embodiment further includes a frequency recovery method based on the distributed ac microgrid, which is characterized in that, as shown in fig. 5, the specific steps are as follows:
step 1, collecting three-phase voltage information v of local alternating current micro-grid bus oi Three-phase current information i oi Local droop controller outputting angular frequency information omega i Andvoltage v of neighbor distributed generation units connected in directed communication topology oj Current i oj Angular frequency information omega j ；
Step 2, according to the three-phase voltage information v of the local alternating current micro-grid bus oi Three-phase current information i oi Local droop controller output angular frequency information omega i And voltage v of a neighboring distributed generation unit connected to a directed communication topology oj Current i oj Angular frequency information omega j Calculating a distributed error index e i (ii) a The method comprises the following specific steps:
the secondary frequency recovery uses an optimal distributed cooperation strategy. A state collector for collecting the three-phase voltage and current information v of the local AC microgrid bus oi 、i oi And angular frequency information omega output by the local droop controller i (ii) a And according to the voltage voj, the current ioj and the angular frequency information omega of the adjacent distributed power generation units j And calculating any distributed error index e by the following formula i ：
In the formula, omega ref For reference voltage, 50Hz was taken. Each DG utilizes its own information and neighbor information to complete frequency recovery with a high degree of consistency.
Step 3, according to the distributed error index e i Judging the state of any distributed power generation unit under attack; the method specifically comprises the following steps:
distributed error index e i And simultaneously transmitting an attack detection link and a distributed optimal cooperative controller. And in the attack detection link, the condition that the frequency fluctuation exceeds +/-0.2 Hz is considered as being attacked or failed, when the bus frequency of the local distributed power generation unit exceeds the limit, the distributed optimal cooperative controller is automatically triggered, and the frequency cooperative recovery is started together with the n distributed power generation units in the microgrid.
Step 4, if the local distributed power generation units are attacked, each distributed power generation unit is based on the system equation and the integral performance index of the distributed power generation unitCollaborative solving of locally distributed optimal auxiliary control inputs
The method specifically comprises the following steps:
the system equation and the integral performance index equation of any distributed power generation unit are as follows:
wherein
Are all positive definite parameter matrices, q i And r i Are all positive scalar parameters. The performance index is divided into two parts, the first part is the cost of the control process, and the second part is the control input energy. Obviously, to achieve the control objective, it is desirable to minimize both process cost and control energy. e.g. of the type i Is a local error index; u. of i Is a local auxiliary control input.
Carrying out input and output feedback linearization on a local control system of any distributed power generation unit, and constructing the following system equation:
the system comprises n DGs, i =1, 2.., n,
and
respectively, system state, system output, and control input.
Is a system matrix.
The idea of solving the functional extreme value with constraint condition according to the variational method is introducedMultiplier lambda i And converting the obtained solution into an unconstrained lagrangian function extremum problem for solving, wherein the unconstrained lagrangian function extremum problem specifically comprises the following steps:
λ i (∞)＝0 (6)；
wherein, the formula (4) and the formula (5) are adjoint equations, the formula (6) is an edge condition, and the formula (7) is a control equation. N is satisfied for all i =1,2 i Hamiltonian for ith DG
Will be lambda i Substitution of formula (7) gives:
for lambda i Derivation of
Further, the following equations (4) and (8) are substituted to obtain:
after substituting formula (9) into formula (5), obtaining:
wherein L is a Laplacian matrix of the system communication topology,
i is a local node; j is a neighbor node.
This formula is satisfied for all i =1,2. Wherein
Is a matrix with 1 for the ith entry and 0 for the remaining entries. Since P and ξ are time-invariant matrices, so
And
are all 0. The equation of formula (10) is split into two parts on both sides: and [ x ] 1 x 2 …x n ] T Relevant moiety, [ x ] 1 x 2 …x n ] T An extraneous portion. The following two equations are constructed:
obtaining P from each of the equations (11) and (12) i,1 ,P i,2 ,...,P i,n And xi i Further carrying out the step (8) to obtain u i . Then u is removed i (i =1, 2.., n) the belt-in (4) yields the following differential equation about the state of the system:
solving the differential equation to obtain the optimal state track
Will P i,1 ,P i,2 ,...,P i,n 、ξ i And
surrogate formula (8) to obtain local distributed optimal auxiliary control input
Step 5, inputting according to local distributed optimal auxiliary control
Calculating an optimal angular frequency reference value
Reference value of optimal angular frequency
And inputting the droop controller so as to complete the compensation of the frequency deviation of the primary controller.
the primary control uses a local controller of a single distributed power generation unit, including droop control and voltage-current double closed-loop control. Three-phase voltage and current information v acquired from alternating current micro-grid bus oi 、i oi Then, the power is input to a power controller after being subjected to abc/dq orthogonal decomposition. The power controller comprises a power calculating device and a droop controller, wherein the power calculating device calculates and obtains active power and reactive power P of the bus end of the microgrid according to input voltage and current information i 、Q i . The droop controller is according to the droop expression:
obtaining a reference voltage input to a voltage controller
And angular frequency omega inputted to the voltage source type inverter i . The voltage controller is based on the reference voltage
Deriving a reference current for an input current controller
The current controller is based on the reference current
And the output current of the voltage source type inverter obtains a reference voltage for controlling the PWM generator to generate the PWM signal. Further based on the PWM signal and the angular frequency omega given by the droop controller i Controlling the inverter output.
The frequency deviation caused by the droop control needs to be compensated by designing a secondary control. To obtain the auxiliary control input for the distributed optimal cooperative controller, equation (14) is differentiated to obtain the following differential equation:
Based on the equations (14) and (15), it is possible to obtain:
the method provided by the invention is completely distributed, each DG has a distributed performance index, global information is not needed, information is exchanged with adjacent DGs only on the basis of a sparse communication network, consensus is achieved in a cooperative mode, and the requirement on a centralized performance index is eliminated; the method has universality to different communication topologies; the method provided by the invention can realize the optimal frequency recovery of each distributed generator set under the attack of the microgrid by using the minimum control energy. And the convergence speed is accelerated by considering the synchronism among the units.
In the present specification, the embodiments 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.
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 invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A frequency recovery method based on a distributed alternating current microgrid is characterized by comprising the following specific steps:
collecting three-phase voltage information v of local AC micro-grid bus oi Three-phase current information i oi Local droop controller output angular frequency information omega i And voltage v of a neighboring distributed generation unit connected to a directed communication topology oj Current i oj Angular frequency information omega j ；
According to local exchange microThree-phase voltage information v of power grid bus oi And three-phase current information i oi Local droop controller output angular frequency information omega i And the voltage v of the neighboring distributed generation units connected to the communication topology oj Current i oj Angular frequency information omega j Calculating a distributed error indicator e i ；
According to a distributed error index e i Judging the attack condition of the local distributed power generation unit;
if any distributed power generation unit is attacked, each distributed power generation unit collaboratively solves local distributed optimal auxiliary control input based on the system equation and integral performance index of each distributed power generation unit
Based on locally distributed optimal auxiliary control input
Calculating an optimal angular frequency reference value
2. The frequency recovery method based on the distributed alternating current micro-grid according to claim 1, wherein the distributed error index e of any distributed power generation unit i The calculation formula of (2) is as follows:
in the formula, a i,j Is an element of the adjacency matrix; omega i Outputting angular frequency information for a local droop controller; omega j Angular frequency information for adjacent distributed power generation units; y is i Outputting a value for the local system; omega ref Is a reference voltage; b is a mixture of i Connecting elements of the gain matrix for the reference values; j is a neighbor node.
3. The frequency recovery method based on the distributed alternating current micro-grid according to claim 1, wherein a system equation of any distributed power generation unit is as follows:
in the formula (I), the compound is shown in the specification,
is the first derivative of the system state; x is the number of i Is the local system state; y is i Outputting a value for the local system; u. u i A local auxiliary control input; i is a local node; A. b and C are both system matrixes.
4. The method of claim 3, wherein the local auxiliary control input u is a frequency recovery input i The expression of (a) is:
in the formula, R is a positive definite constant matrix; r is i Is a positive scalar quantity; i is a local node; b is a system matrix; x is the number of n Is a state variable of the nth distributed generation unit; p is i,n Is a lambd of a lambertian multiplier i A matrix of coefficients relating to the state variables; xi shape i Lambda is a multiplier of Langerday i A matrix of coefficients independent of the state variables.
5. The method of claim 1, wherein the local distributed optimal auxiliary control input is used as a frequency recovery input for the distributed ac microgrid
The step of obtainingThe method comprises the following steps:
constructing a system equation and an integral performance index equation of any distributed power generation unit, and constructing an integral performance index J i The expression of (c) is:
in the formula, e i Is a local error index; u. u i A local auxiliary control input; q. q of i 、r i Are all positive scalars; q and R are both positive definite constant matrixes;
introducing lagrange multiplier lambda i Obtaining local auxiliary control input u based on system equation and integral performance index equation of each distributed power generation unit i The expression of (1);
for lagrange multiplier lambda i System equation and integral performance index equation of each distributed power generation unit and auxiliary control input u i The expression of (2) is subjected to multiple combined operations to obtain an optimal state track;
computing local distributed optimal auxiliary control input based on optimal state trajectory
6. The frequency recovery method based on the distributed alternating current micro-grid according to claim 1, wherein any optimal angular frequency reference value
The calculation formula of (2) is as follows:
in the formula u i A local auxiliary control input; d P,i Is a droop control coefficient; p i Active for output of local VSIAnd (3) power.
7. A frequency recovery system based on a distributed alternating current micro-grid is characterized by comprising a communication network, a state collector, an attack detection module, a distributed optimal cooperative controller, a power controller, a voltage controller, a current controller and a voltage source type inverter;
a communication network for transmission of data;
the state collector is used for collecting three-phase voltage information v of a local alternating current micro-grid bus oi Three-phase current information i oi Local droop controller outputting angular frequency information omega i And the voltage v of the adjacent distributed generation unit of any one of the distributed generation units oj Current i oj Angular frequency information omega j ；
An attack detection step, which is used for judging whether each distributed power generation unit is attacked or not and sending a control signal to the distributed optimal cooperative controller;
distributed optimal cooperative controller for computing local distributed optimal auxiliary control input
And an optimum angular frequency reference value
A power controller for controlling the power according to the optimal angular frequency reference value
Completing the compensation of the frequency deviation;
a voltage controller for controlling the voltage according to the reference voltage
Deriving a reference current for an input current controller
A current controller for controlling the current according to the reference current
Obtaining a reference voltage for controlling a PWM generator to generate a PWM signal according to the output current of the voltage source type inverter;
voltage source type inverter for controlling angular frequency omega of power controller according to PWM signal i And outputting the voltage.
8. The frequency recovery system based on the distributed alternating current micro-grid according to claim 7, wherein the system is divided into a physical layer and an information layer;
the physical layer comprises n distributed power generation units, and the n distributed power generation units are connected to a local microgrid bus through a voltage source type inverter;
the information layer is a directed connection communication topology containing a spanning tree.
9. The frequency recovery system based on the distributed ac microgrid of claim 8, wherein the directional connection communication topology is represented by G (V, E, a, B), wherein V is a node set; e is a directed edge set; a is an adjacency matrix of the topology; b is the connection gain matrix.
10. The frequency recovery system based on the distributed alternating current microgrid of claim 7, characterized in that the microgrid is composed of n distributed power generation units and m integrated loads.
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