CN108471109A - The univesral distribution formula control method and system of the more micro-grid systems of direct current - Google Patents
The univesral distribution formula control method and system of the more micro-grid systems of direct current Download PDFInfo
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Abstract
The embodiment of the present invention provides a kind of univesral distribution formula control method of more micro-grid systems of direct current and system, control method include：Based on multiple micro-capacitance sensor control instruction parameters, the corresponding control instruction of any direct-current grid in the more micro-grid systems of the direct current is obtained by Load flow calculation, wherein the more micro-grid systems of direct current include multiple direct-current grids；The corresponding control instruction of any direct-current grid is sent to corresponding direct-current grid, to realize that the univesral distribution formula of the more micro-grid systems of the direct current controls.The univesral distribution formula control method and system of the more micro-grid systems of direct current provided in an embodiment of the present invention, by obtaining the corresponding control instruction of any direct-current grid, the micro-capacitance sensor that can be directed under different control laws provides corresponding control reference value, can be realized as optimized operation without changing bottom control.Control method provided in an embodiment of the present invention is distributed, is not necessarily to Centralized Controller.
Description
Technical Field
The embodiment of the invention relates to the field of micro-grids, in particular to a unified distributed control method and system for a direct-current multi-micro-grid system.
Background
The direct-current multi-micro-grid system refers to an electric power system consisting of a plurality of direct-current micro-grids, and the optimal operation of the direct-current multi-micro-grid system is always an important topic. The main expression is how each microgrid controls the voltage and the generated power of the microgrid, so that the power generation cost of the whole system is minimized.
Various converter devices may exist in the direct-current multi-microgrid system, and manufacturers and control modes of the converter devices may be different, so that optimal operation is difficult to achieve. However, the control strategy of simultaneously replacing all the devices is difficult to implement in engineering, and how to design the optimal controller without changing the bottom control of the converter is an urgent problem to be solved.
It should be noted that the Optimal Power Flow (OPF) refers to the Power Flow distribution that can adjust the available control variables, such as the output Power of the generator, the adjustable node voltage, etc., to satisfy all the operation constraints and optimize the performance index of the system, such as the Power generation cost or the network loss, when the structural parameters and the load conditions of the system are given.
For the control operation problem of the direct current microgrid, the existing research is realized based on consistency control (Consensus). Namely, an optimization problem with the power generation cost as an objective function is established firstly, and the constraint condition is the power balance in the system, namely all the total power generation is equal to the total load. Then, the marginal power generation costs of the micro grids are equal through consistency control (Consensus), and an optimal power control reference value is obtained. And finally, sending the reference value to each microgrid, thereby realizing economic optimization. Mathematically, if the marginal generation costs of each microgrid are equal and the power is balanced, the system operates optimally.
Firstly, however, the prior art needs to change the original control strategy of each direct current microgrid, and is difficult to implement in engineering; secondly, the prior art can not ensure that the power generation capacity and the voltage control command also meet the upper and lower limit constraints in the transient process, and easily causes the dangers of infeasibility of command or overhigh voltage and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the embodiment of the invention provides a unified distributed control method and system for a direct-current multi-microgrid system.
The embodiment of the invention provides a unified distributed control method of a direct-current multi-microgrid system, which comprises the following steps: based on a plurality of microgrid control instruction parameters, obtaining a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system through load flow calculation, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids; and sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system.
The embodiment of the invention provides a unified distributed control system of a direct-current multi-microgrid system, which comprises: the acquisition instruction module is used for acquiring a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system through load flow calculation based on a plurality of microgrid control instruction parameters, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids; and the control module is used for sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system.
According to the unified distributed control method and system for the direct-current multi-microgrid system, the control instruction corresponding to any one direct-current microgrid is obtained, and the corresponding control reference value can be given for the microgrids under different control rules, so that optimal operation can be achieved without changing bottom control. The control method provided by the embodiment of the invention is distributed, and a centralized controller is not needed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a flowchart of an embodiment of a unified distributed control method for a dc multi-microgrid system according to the present invention;
fig. 2 is a strategy diagram of a unified distributed control method of the dc multi-microgrid system according to the embodiment of the present invention;
fig. 3 is a block diagram of an embodiment of a unified distributed control system of the dc multi-microgrid system according to the present invention;
FIG. 4 is a topology diagram of a simulation system in an embodiment of the invention;
fig. 5 is a power generation amount dynamic diagram of the microgrid 2 and the microgrid 5 in the embodiment of the present invention;
fig. 6 is a voltage dynamic diagram of the microgrid 3 and the microgrid 4 in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a flowchart of an embodiment of a unified distributed control method for a dc multi-microgrid system according to the present invention, where as shown in fig. 1, the control method includes: s1, obtaining a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system through load flow calculation based on a plurality of microgrid control instruction parameters, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids; and S2, sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system.
Specifically, the original control strategy of each direct current microgrid needs to be changed, which is difficult to realize in engineering; and the power generation capacity and the voltage control command can not be guaranteed to meet the upper and lower limit constraints in the transient process, so that the risks of command infeasibility or over-high voltage and the like are easily caused. The invention aims to provide a unified distributed control method and a system for a direct-current multi-microgrid system, which can realize optimal operation without changing bottom control and are always physically feasible for power and voltage reference values of a microgrid adopting constant power control and constant voltage control.
Before explaining the scheme in the embodiment of the present invention, the dc microgrid in the embodiment of the present invention will be described.
The DC multi-microgrid system consists of DGs (power supplies) and loads which are connected through a connecting line, and the whole DC power system can use a connection diagramAnd (4) showing. Wherein the set of DGs is
The set of lines between DGs isIf a tie exists between two DGs (i, k, respectively), it is expressed as (i, k) ∈ and abbreviated as i to k. The resistance of the line (i, k) is denoted rikThe power from DG i to DGk is denoted as PikThe current of the line (I, k) is IikLet m ═ epsilon | denote the number of lines.
Let DG i generate power asCorresponding to a load ofThe voltage at its node is denoted as Vi. Generally, there are three main control modes for DG, namely constant power control, constant voltage control and droop control. Wherein the constant power control and the constant voltage control need to provide corresponding reference values, and the droop control is as follows:
wherein v isi=Vi 2Denotes the square of the current, kiIn order to obtain the sag factor,for the voltage squared reference value, k in this reportiAndare all constant and are all provided with the same power,is a reference value for power in droop control. In IPS, the control methods that are frequently used are constant voltage control and droop control.
For a direct current network, the power flow equation of each node is as follows:
wherein N isiRepresenting the set of DGs directly connected to DGi.
The network power flow equation is as follows:
Pik+Pki＝riklik；
wherein likIs the square of the line current.
The following operational constraints also need to be considered in JC power system operation:
which is the generated output constraint of the DG,is the upper limit of the generated output.
Which is a constraint on the voltage at the node,respectively, the upper and lower bounds of the node voltage.
After the dc microgrid in the embodiment of the present invention is described, a unified distributed control method of the dc multi-microgrid system in the embodiment of the present invention is described below.
Firstly, a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system is obtained through load flow calculation based on a plurality of microgrid control instruction parameters, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids. The load flow calculation is a calculation method in the field of micro-grids.
And then, sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system. Each direct current microgrid corresponds to a control command.
It should be noted that the plurality of microgrid control instruction parameters include a load of each dc microgrid, a power generation amount of each dc microgrid, a voltage square of each dc microgrid, a tie line power connected between the dc microgrids, a current square connected between the dc microgrids, a droop control parameter of each dc microgrid, a line resistance between the dc microgrids, an upper and lower voltage bound of each dc microgrid, an upper power generation limit of each dc microgrid, and a power generation cost parameter of each dc microgrid.
According to the unified distributed control method for the direct-current multi-microgrid system, the control instruction corresponding to any one direct-current microgrid is obtained, and the corresponding control reference values can be given for the microgrids under different control rules, so that optimal operation can be achieved without changing bottom control. The control method provided by the embodiment of the invention is distributed, and a centralized controller is not needed.
Based on the above embodiment, the obtaining of the control instruction corresponding to any one of the dc micro grids in the dc multi-micro grid system through load flow calculation based on the multiple micro grid control instruction parameters specifically includes: inputting a plurality of microgrid control instruction parameters into an optimal power flow model of the direct-current multi-microgrid system; and solving the optimal power flow model of the direct-current multi-microgrid system by a primal-dual gradient method, and acquiring a control instruction corresponding to any direct-current microgrid based on a solving result.
According to the unified distributed control method for the direct-current multi-microgrid system, provided by the embodiment of the invention, the optimal power flow model of the direct-current multi-microgrid system is solved, and a unified control mode is designed based on a dual-primary gradient algorithm, so that corresponding control reference values can be provided for the microgrid under different control rules.
Based on the above embodiment, the inputting the multiple microgrid control instruction parameters into the optimal power flow model of the dc multi-microgrid system further includes: constructing an optimal power flow model of the direct-current multi-microgrid system through the following formula:
Pik+Pki＝riklik),i～k；vi-vk＝rik(Pik-Pki),i～k；
wherein,
in which the number of the first and second groups is reduced,is the load of the ith dc microgrid,is the power generation amount of the ith direct current micro-grid, viIs the voltage square, P, of the ith DC microgridikThe i-th DC microgrid is connected with the tie line power l of the k-th DC microgridikThe square of the connecting line current, k, of the ith direct current micro-grid connected with the kth direct current micro-gridiFor droop control parameters, r, of the ith DC microgridikThe line resistances of the ith direct current micro-grid and the kth direct current micro-grid,V iis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith dc microgrid,the power generation power of the ith direct current micro-grid is an upper bound, i represents the power supply of the ith direct current micro-grid, N is the number of the power supplies of the direct current micro-grid, and y isiAnd ziFor the intermediate variable, k represents the supply of the kth DC microgrid, vkIs the voltage square, P, of the kth DC microgridkiThe connecting line power of the kth DC micro-grid to the ith DC micro-grid, rikIs the line resistance of the kth direct current micro-grid and the ith direct current micro-grid, k is k belongs to NiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value, k, of the ith DC micro-gridiIs the droop coefficient of the ith direct current microgrid,and f () is an objective function of the direct current microgrid, wherein f () is a reference value of power in droop control of the ith direct current microgrid.
Based on the above embodiment, in the optimal power flow model of the direct-current multi-microgrid system, P iskiAnd vkObtained by the following formula:
wherein, PkiConnecting line power, v, of the kth DC microgrid to the ith DC microgridkIs the voltage square, P, of the kth DC microgridikThe tie line power, r, of the ith DC microgrid to the kth DC microgridikIs the line resistance, I, of the ith DC microgrid and the kth DC microgridikIs the current between the ith DC microgrid and the kth DC microgrid, viThe square of the voltage of the ith direct current micro-grid.
It should be noted that the neighbor information in the above formula is PkiAnd vk. At the above-mentioned solution PkiAnd vkIn the course of (1), the current I of the lineikCan be obtained by local measurement. Thus, only the variable ρkiIt needs to be obtained from the neighbor DG, which can minimize the traffic.
According to the unified distributed control method of the direct-current multi-microgrid system, only local information and information of adjacent DGs are needed in the process of solving the optimal power flow model, unified distributed control can be achieved, and an integrated controller is not needed.
Based on the above embodiment, solving the optimal power flow model of the dc multi-microgrid system by a primal-dual gradient method specifically includes:
based on a primal-dual gradient method, solving the optimal power flow model of the direct-current multi-microgrid system by the following algorithm:
wherein,is the power generation amount of the ith direct current micro-grid, aiAnd biIs the power generation cost parameter, y, of the ith direct current micro-gridiAnd ziIs an intermediate variable, kiI represents the power supply of the ith direct current micro-grid for the droop control parameter of the ith direct current micro-grid,is the ith direct currentUpper bound of generated power, v, of the microgridiIs the voltage square of the ith DC microgrid, NiFor the set of all DC microgrid connected to the ith DC microgrid, rikIs the line resistance, P, of the kth DC microgrid and the ith DC microgridikConnecting the ith direct current micro-grid with the k direct current micro-grid, wherein k represents the power supply of the k direct current micro-grid,V iis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith DC microgrid,/ikIs the square of the current between the ith dc microgrid and the kth dc microgrid,k is the load of the ith direct current micro-gridiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value of the ith direct current micro-grid,is a reference value of power in droop control of the ith DC microgrid, PkiConnecting line power, v, of the kth DC microgrid to the ith DC microgridkIs the voltage square, rho, of the kth DC microgridik、μi、ρki、λik、γikAnd eiAre all variables obtained by calculation.
In addition, the operatorRepresenting the derivation.
For any xi,ai,biAnd a isi≥biIs provided with
OperatorIs defined as follows:
the algorithm (7) is fully distributed, with each DG computing internal variablesOnly local information and information P of adjacent DGs are neededki,vk,ρki,k∈Ni。
According to the unified distributed control method of the direct-current multi-microgrid system, only local information and information of adjacent DGs are needed in the process of solving the optimal power flow model, unified distributed control can be achieved, and an integrated controller is not needed.
Based on the above embodiment, the control instruction corresponding to any one of the dc micro-grids is any one of a constant power control instruction, a constant voltage control instruction, and a droop control instruction, where: the constant power control instruction is a power reference value; the constant voltage control instruction is a voltage reference value; the droop control instruction is a droop control power reference value.
In a direct current system, different power supplies may adopt different control modes, mainly including constant power control, constant voltage control and droop control, and the control methods can provide different reference values for various control methods. For constant power control and constant voltage control, the control method can provide reference values for power and voltage, and for droop control, the control method can provide reference values for power in droop control.
Based on the above embodiment, the obtaining of the control instruction corresponding to any one of the dc micro grids in the dc multi-micro grid system through load flow calculation based on the multiple micro grid control instruction parameters specifically includes: based on a plurality of microgrid control instruction parameters, obtaining any one of a power reference value, a voltage reference value and a droop control power reference value corresponding to any one direct current microgrid through load flow calculation; and acquiring any one of a constant power control instruction, a constant voltage control instruction and a droop control instruction of any corresponding direct current micro-grid according to any one of a power reference value, a voltage reference value and a droop control power reference value corresponding to any direct current micro-grid.
Fig. 2 is a schematic diagram of a unified distributed control method of a dc multi-microgrid system according to an embodiment of the present invention, and please refer to fig. 2 in this embodiment.
In FIG. 2, IrefIs a current reference value, v, of the current looprefIs a voltage reference value for the voltage loop,the power reference instruction provided for the algorithm,the voltage reference command provided for the algorithm,droop control power reference commands provided for the algorithm. The left half part of the figure is the algorithm proposed by the report, and the other half part is a control block diagram with different control modes. The input variable required by each DG is local informationAnd neighbor information Pki,vk,ρki,k∈Ni。
The uniform distributed control method of the direct-current multi-microgrid system provided by the embodiment of the invention provides corresponding control reference values for direct-current microgrids under different control laws, so that optimal operation can be realized without changing bottom control, and the power and voltage reference values of the microgrid adopting constant-power control and constant-voltage control are always physically feasible.
Based on the foregoing embodiments, this embodiment provides a unified distributed control system for a dc multi-microgrid system, and fig. 3 is a block diagram of the unified distributed control system for a dc multi-microgrid system in the embodiment of the present invention, and as shown in fig. 3, the control system includes: the instruction obtaining module 1 is configured to obtain a control instruction corresponding to any one direct-current microgrid in the direct-current multi-microgrid system through load flow calculation based on a plurality of microgrid control instruction parameters, wherein the direct-current multi-microgrid system comprises a plurality of direct-current microgrids; and the control module 2 is used for sending the control instruction corresponding to any one direct-current micro grid to the corresponding direct-current micro grid so as to realize the uniform distributed control of the direct-current multi-micro-grid system.
It should be noted that, the instruction obtaining module 1 and the control module 2 cooperate to execute the unified distributed control method of the dc multi-microgrid system in the foregoing embodiment, and specific functions of the system refer to the foregoing embodiment of the obtaining method, which is not described herein again.
Based on the above embodiment, the instruction obtaining module specifically includes: the data input sub-module is used for inputting a plurality of microgrid control instruction parameters into an optimal power flow model of the direct current multi-microgrid system; and the solving and obtaining submodule is used for solving the optimal power flow model of the direct-current multi-microgrid system through a primal-dual gradient method and obtaining a control instruction corresponding to any direct-current microgrid based on a solving result.
Based on the above embodiment, the control system further includes a construction model module, where the construction model module is configured to construct an optimal power flow model of the dc multi-microgrid system according to the following formula:
Pik+Pki＝riklik),i～k；vi-vk＝rik(Pik-Pki),i～k；
wherein,
in which the number of the first and second groups is reduced,is the load of the ith dc microgrid,is the power generation amount of the ith direct current micro-grid, viIs the voltage square, P, of the ith DC microgridikThe i-th DC microgrid is connected with the tie line power l of the k-th DC microgridikThe square of the connecting line current, k, of the ith direct current micro-grid connected with the kth direct current micro-gridiFor droop control parameters, r, of the ith DC microgridikThe line resistances of the ith direct current micro-grid and the kth direct current micro-grid, iVis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith dc microgrid,is the upper limit of the generated power of the ith direct current micro-grid, i represents the power supply of the ith direct current micro-grid, and N is the direct current micro-gridNumber of power supplies of the network, yiAnd ziFor the intermediate variable, k represents the supply of the kth DC microgrid, vkIs the voltage square, P, of the kth DC microgridkiThe connecting line power of the kth DC micro-grid to the ith DC micro-grid, rikIs the line resistance of the kth direct current micro-grid and the ith direct current micro-grid, k is k belongs to NiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value, k, of the ith DC micro-gridiIs the droop coefficient of the ith direct current microgrid,and f () is an objective function of the direct current microgrid, wherein f () is a reference value of power in droop control of the ith direct current microgrid.
The effect of the present invention will be further described below by way of an example as a preferred embodiment.
Fig. 4 is a topological diagram of a simulation system in an embodiment of the present invention, and as shown in fig. 4, the dc multi-microgrid system is composed of 6 dc microgrids, and line resistances are shown in the figure. The parameters of 6 dc microgrid are shown in table 1.
TABLE 1 parameter table of DC microgrid
Wherein the objective function of each microgrid isAs a load of each micro grid,is the upper limit of the power generation,is the upper and lower voltage bounds, kiThe sag factor.
And constructing an optimal power flow model for the direct-current multi-microgrid system through the embodiment.
And inputting a plurality of microgrid control instruction parameters into the optimal power flow model of the direct-current multi-microgrid system.
And solving the optimal power flow model of the direct-current multi-microgrid system by a primal-dual gradient method, and acquiring a control instruction corresponding to any direct-current microgrid based on a solving result.
And acquiring a control instruction corresponding to any direct current micro-grid based on the solving result, and sending the control instruction corresponding to any direct current micro-grid to the corresponding direct current micro-grid so as to realize the uniform distributed control of the direct current multi-micro-grid system.
For the present embodiment, the microgrid 1 and the microgrid 6 adopt droop control, the microgrid 2 and the microgrid 5 adopt constant power control, and the microgrid 3 and the microgrid 4 adopt constant voltage control. The simulation condition is that at 1s, the load of each area is increased from (41,40,42,39,42,40) kW to (51,50,52,49,52,50) kW, and each microgrid increases the output to meet the load change.
The steady-state simulation result of the dc multi-microgrid system in the present embodiment is shown in table 2.
TABLE 2 Steady-State simulation results Table
In table 2, the second column indicates the power generation of each microgrid, the third column indicates the result obtained by the centralized method, the fourth column indicates the difference between them, the fifth column indicates the droop control power reference value obtained in the present example, the sixth column indicates the result obtained by the centralized method, and the seventh column indicates the difference between them. It can be seen that the control method in the embodiment and the centralized method obtain substantially the same results, thereby verifying the effect of the control method in the embodiment.
Next, a transient simulation result of the embodiment is described, fig. 5 is a dynamic graph of power generation amounts of the microgrid 2 and the microgrid 5 in the embodiment of the present invention, and fig. 6 is a dynamic graph of voltages of the microgrid 3 and the microgrid 4 in the embodiment of the present invention, please refer to fig. 5 and fig. 6.
In the conventional control command without considering the power generation capacity, a control command exceeding the power generation capacity occurs in a transient process, which cannot be realized in a practical system, whereas the control command obtained by the control method of the embodiment of the present invention is always within the power generation capacity range even in the transient process. Although the steady state results obtained by the two methods are the same, the control method of the embodiment of the invention is more reasonable.
In the conventional control command without considering the voltage amplitude limitation, the transient process has the control command exceeding the voltage amplitude limitation, which is not beneficial to the safe operation of the rectifier in the practical system, and the control command obtained by the control method of the embodiment of the invention is always within the allowable range even during the transient process. Although the steady state results obtained by the two methods are the same, the control method of the embodiment of the invention is more reasonable.
According to the unified distributed control method and system for the direct-current multi-microgrid system, the control instruction corresponding to any one direct-current microgrid is obtained, and the corresponding control reference value can be given for the microgrids under different control rules, so that optimal operation can be achieved without changing bottom control. The control method provided by the embodiment of the invention is distributed, and a centralized controller is not needed.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A unified distributed control method of a direct current multi-microgrid system is characterized by comprising the following steps:
based on a plurality of microgrid control instruction parameters, obtaining a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system through load flow calculation, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids;
and sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system.
2. The control method according to claim 1, wherein the obtaining of the control instruction corresponding to any one of the dc micro grids in the dc multi-micro grid system through load flow calculation based on the plurality of micro grid control instruction parameters specifically includes:
inputting a plurality of microgrid control instruction parameters into an optimal power flow model of the direct-current multi-microgrid system;
and solving the optimal power flow model of the direct-current multi-microgrid system by a primal-dual gradient method, and acquiring a control instruction corresponding to any direct-current microgrid based on a solving result.
3. The control method according to claim 2, wherein the inputting the plurality of microgrid control command parameters into the optimal power flow model of the direct current multi-microgrid system further comprises:
constructing an optimal power flow model of the direct-current multi-microgrid system through the following formula:
Pik+Pki＝riklik),i～k；vi-vk＝rik(Pik-Pki),i～k；
i～k；
wherein,
in which the number of the first and second groups is reduced,is the load of the ith dc microgrid,is the power generation amount of the ith direct current micro-grid, viIs the voltage square, P, of the ith DC microgridikThe i-th DC microgrid is connected with the tie line power l of the k-th DC microgridikThe square of the connecting line current, k, of the ith direct current micro-grid connected with the kth direct current micro-gridiFor droop control parameters, r, of the ith DC microgridikThe line resistances of the ith direct current micro-grid and the kth direct current micro-grid,V iis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith dc microgrid,the power generation power of the ith direct current micro-grid is an upper bound, i represents the power supply of the ith direct current micro-grid, N is the number of the power supplies of the direct current micro-grid, and y isiAnd ziFor the intermediate variable, k represents the supply of the kth DC microgrid, vkIs the voltage square, P, of the kth DC microgridkiThe connecting line power of the kth DC micro-grid to the ith DC micro-grid, rikIs the line resistance of the kth direct current micro-grid and the ith direct current micro-grid, k is k belongs to NiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value, k, of the ith DC micro-gridiIs the droop coefficient of the ith direct current microgrid,and f () is an objective function of the direct current microgrid, wherein f () is a reference value of power in droop control of the ith direct current microgrid.
4. The control method according to claim 3, wherein P is an optimal power flow model of the DC multi-microgrid systemkiAnd vkObtained by the following formula:
wherein, PkiConnecting line power, v, of the kth DC microgrid to the ith DC microgridkIs the voltage square, P, of the kth DC microgridikThe tie line power, r, of the ith DC microgrid to the kth DC microgridikIs the line resistance, I, of the ith DC microgrid and the kth DC microgridikIs the current between the ith DC microgrid and the kth DC microgrid, viThe square of the voltage of the ith direct current micro-grid.
5. The control method according to claim 2, wherein the solving of the optimal power flow model of the direct current multi-microgrid system through a primal-dual gradient method specifically comprises:
based on a primal-dual gradient method, solving the optimal power flow model of the direct-current multi-microgrid system by the following algorithm:
wherein,is the power generation amount of the ith direct current micro-grid, aiAnd biIs the power generation cost parameter, y, of the ith direct current micro-gridiAnd ziIs an intermediate variable, kiI represents the power supply of the ith direct current micro-grid for the droop control parameter of the ith direct current micro-grid,is the upper bound of the generated power of the ith direct current micro-grid, viIs the voltage square of the ith DC microgrid, NiFor the set of all DC microgrid connected to the ith DC microgrid, rikIs the line resistance, P, of the kth DC microgrid and the ith DC microgridikConnecting the ith direct current micro-grid with the k direct current micro-grid, wherein k represents the power supply of the k direct current micro-grid,V iis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith DC microgrid,/ikIs the square of the current between the ith dc microgrid and the kth dc microgrid,k is the load of the ith direct current micro-gridiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value of the ith direct current micro-grid,is a reference value of power in droop control of the ith DC microgrid, PkiConnecting line power, v, of the kth DC microgrid to the ith DC microgridkIs the voltage square, rho, of the kth DC microgridik、μi、ρki、λik、γikAnd eiAre all variables obtained by calculation.
6. The control method according to claim 1, wherein the control command corresponding to any one of the dc micro-grids is any one of a constant power control command, a constant voltage control command, and a droop control command, wherein:
the constant power control instruction is a power reference value; the constant voltage control instruction is a voltage reference value; the droop control instruction is a droop control power reference value.
7. The control method according to claim 6, wherein the obtaining of the control instruction corresponding to any one of the direct current micro grids in the direct current multi-micro grid system through load flow calculation based on the plurality of micro grid control instruction parameters specifically includes:
based on a plurality of microgrid control instruction parameters, obtaining any one of a power reference value, a voltage reference value and a droop control power reference value corresponding to any one direct current microgrid through load flow calculation;
and acquiring any one of a constant power control instruction, a constant voltage control instruction and a droop control instruction of any corresponding direct current micro-grid according to any one of a power reference value, a voltage reference value and a droop control power reference value corresponding to any direct current micro-grid.
8. The utility model provides a unified distributed control system of many microgrid systems of direct current which characterized in that includes:
the acquisition instruction module is used for acquiring a control instruction corresponding to any one direct current microgrid in the direct current multi-microgrid system through load flow calculation based on a plurality of microgrid control instruction parameters, wherein the direct current multi-microgrid system comprises a plurality of direct current microgrids;
and the control module is used for sending the control instruction corresponding to any one direct current micro grid to the corresponding direct current micro grid so as to realize the uniform distributed control of the direct current multi-micro grid system.
9. The control system according to claim 8, wherein the instruction obtaining module specifically includes:
the data input sub-module is used for inputting a plurality of microgrid control instruction parameters into an optimal power flow model of the direct current multi-microgrid system;
and the solving and obtaining submodule is used for solving the optimal power flow model of the direct-current multi-microgrid system through a primal-dual gradient method and obtaining a control instruction corresponding to any direct-current microgrid based on a solving result.
10. The control system of claim 9, further comprising a construction model module configured to construct an optimal power flow model of the dc microgrid system according to the following formula:
Pik+Pki＝riklik),i～k；vi-vk＝rik(Pik-Pki),i～k；
i～k；
wherein,
in which the number of the first and second groups is reduced,is the load of the ith dc microgrid,is the power generation amount of the ith direct current micro-grid, viIs the voltage square, P, of the ith DC microgridikThe i-th DC microgrid is connected with the tie line power l of the k-th DC microgridikThe square of the connecting line current, k, of the ith direct current micro-grid connected with the kth direct current micro-gridiFor droop control parameters, r, of the ith DC microgridikThe line resistances of the ith direct current micro-grid and the kth direct current micro-grid,V iis the upper voltage bound of the ith dc microgrid,is the lower voltage bound of the ith dc microgrid,the power generation power of the ith direct current micro-grid is an upper bound, i represents the power supply of the ith direct current micro-grid, N is the number of the power supplies of the direct current micro-grid, and y isiAnd ziFor intermediate variables, k represents the electricity of the kth DC microgridSource, vkIs the voltage square, P, of the kth DC microgridkiThe connecting line power of the kth DC micro-grid to the ith DC micro-grid, rikIs the line resistance of the kth direct current micro-grid and the ith direct current micro-grid, k is k belongs to NiRepresenting all the dc micro grids connected to the ith dc micro grid,is the voltage square reference value, k, of the ith DC micro-gridiIs the droop coefficient of the ith direct current microgrid,and f () is an objective function of the direct current microgrid, wherein f () is a reference value of power in droop control of the ith direct current microgrid.
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