CN109787221A - A kind of micro-capacitance sensor electric energy safe economic load dispatching method and system - Google Patents
A kind of micro-capacitance sensor electric energy safe economic load dispatching method and system Download PDFInfo
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Abstract
The present invention provides a kind of micro-capacitance sensor electric energy safe economic load dispatching methods.The method includes: to bring the adjustable resource operation data in micro-capacitance sensor into pre-establish micro-capacitance sensor moving model, the active power output reference value of the adjustable resource in the micro-capacitance sensor is obtained by Optimization Solution in conjunction with renewable energy prediction data and the prediction data of load, and Load flow calculation is carried out based on the active power output reference value, obtain the voltage initial value of each node；For the node that voltage out-of-limit occurs, the active power output range of adjustable resource is corrected by the voltage control strategy of setting, until voltage out-of-limit is eliminated, and the minimum objective function of micro-capacitance sensor controllable electric generator group total operating cost converges to optimal solution.Technical solution provided by the invention nets the active power output of interior adjustable resource by optimization, realizes the optimized operation of micro-capacitance sensor.
Description
Technical Field
The invention relates to the field of optimal scheduling of a power distribution network, in particular to a safe and economic scheduling method and system for micro-grid power.
Background
Under the practical background of increasingly exhausted fossil energy and the economic development requirement of clean low carbon, the traditional power grid construction mode of centralized power generation and remote power transmission shows greater and greater limitations. In order to improve the energy structure, guarantee the energy safety and realize the sustainable development of the economic society, the development and utilization of renewable energy are gradually paid attention by the nation. However, when a large number of distributed power supplies are connected to the power grid, adverse effects are brought to the power grid, and the safe and stable operation of the system is threatened.
The microgrid technology is a new power technology developed in recent years, can integrate a large amount of distributed new energy power generation, and is helpful for solving various problems faced by the traditional power distribution network. However, at present, the safety control technology of the microgrid is still immature, and related research for optimizing and scheduling the electric energy of the microgrid and considering the safe operation is lacked.
Disclosure of Invention
Aiming at the research blank in the field, the invention provides a safe and economic dispatching method for micro-grid electric energy, which has the characteristics of realizing the optimized dispatching of the micro-grid electric energy and considering the operation safety and the economy of the micro-grid.
The technical scheme provided by the invention is as follows:
a safe and economic dispatching method for microgrid electric energy comprises the following steps:
the method comprises the steps of substituting adjustable resource operation data in the microgrid into a microgrid operation model which is established in advance, and obtaining an active output reference value of adjustable resources in the microgrid within a set time scale through optimization solution according to renewable energy source prediction data and load prediction data which are collected in advance;
performing load flow calculation on the micro-grid based on the active power output reference value, the pre-collected renewable energy source prediction data and the load prediction data to obtain a voltage initial value of each node, and determining a node with voltage out-of-limit according to the voltage initial value of each node;
correcting the active output range of the adjustable resource by a preset voltage control strategy aiming at a node with voltage out-of-limit, feeding back the corrected active output range of the adjustable resource as a constraint condition to the micro-grid operation model for optimization solution again until the voltage out-of-limit is eliminated, and obtaining an optimal active output value;
the adjustable resources in the microgrid comprise: controllable generating set, energy storage and flexible load.
Preferably, the modifying the active power output range of the adjustable resource by using a preset voltage control strategy for the node where the voltage out-of-limit occurs includes:
based on the node with the out-of-limit generated voltage, establishing a network matrix of the out-of-limit generated cause degree of the adjustable resource node voltage in the micro-grid and an indication matrix indicating the position and the moment of the out-of-limit generated voltage of the adjustable resource node in the micro-grid;
multiplying the network matrix and the indication matrix to obtain a dynamic gain matrix which reflects that each adjustable resource in the micro-grid adjusts the level of the self output range in order to eliminate voltage out-of-limit;
and correcting the active output range of the adjustable resources in the microgrid according to the dynamic gain matrix.
Further, the network matrix is:
wherein ,Ni,jThe size of the cause of voltage out-of-limit on the node j for the ith adjustable resource, NUnitIs the total number of tunable resources, NNodeIs the total number of nodes;
the indication matrix is:
wherein ,Ij,tAnd the voltage change rate of the node j when the voltage exceeds the threshold at the time T is shown, and T is the total time period number of the optimized scheduling.
Furthermore, the size N of the cause of voltage out-of-limit of the ith adjustable resource to the node ji,jIs determined by the following formula:
wherein ,LijFor tunable resources i andthe length of the line between nodes j.
Further, the voltage change rate I of the node j when the voltage overlimit occurs at the time tj,tThe following formula:
Ij,t＝λjΔVj
wherein ,λjThe voltage threshold-crossing parameter is a variable 0/1, and when the voltage threshold-crossing occurs at the node j, lambda isjTake the value 1, otherwise, λjThe value is 0; Δ VjIs the rate of change of voltage.
Further, the voltage change rate Δ VjThe following formula:
wherein ,is the rated voltage of node j, VjAnd calculating the initial voltage value of the node j for the load flow.
Further, the dynamic gain matrix is:
wherein ,Ai,tThe level of the self-output range is adjusted for each adjustable resource in order to eliminate voltage violations.
Further, the active power output range of the tunable resource is modified by the following formula:
wherein ,is the rated upper limit of the output of the adjustable resource i,is the rated lower output limit of the adjustable resource i,the minimum power that can be emitted at time t after the output is adjusted for the adjustable resource i,and adjusting the maximum power which can be emitted at the time t after the output is performed on the adjustable resource i.
Preferably, the establishing of the microgrid operation model comprises:
according to the adjustable resource operation data in the microgrid, the economic and environmental benefits are calculated, and the cost function and the CO of the controllable generator set of the microgrid are established2The discharge function, the charge and discharge benefits of the stored energy and the charge cost of the flexible load;
cost function based on controllable generator set, CO of controllable generator set2Determining a target function with the lowest total operation cost of the micro-grid controllable generator set according to the discharge function, the charge-discharge income of stored energy and the charge cost of the flexible load;
determining the rated upper and lower output limits of the controllable generator set as the initial constraint of the output of the controllable generator set according to the operation data of the controllable generator set;
and determining energy and power constraint of the stored energy and power constraint of the flexible load according to the charging and discharging characteristics of the stored energy and the flexible load.
Further, the objective function of the minimum total operating cost of the microgrid controllable generator set is as follows:
wherein ,CtotalFor the total day-ahead operating cost of the micro-grid,in order to control the power generation cost of the generator set,CO for controllable generator sets2The cost of the discharge is high,for the charging and discharging benefit of the stored energy,the charging cost for the flexible load, T is the total time period number of the optimized scheduling, NGenThe total number of the controllable generator sets.
Further, the power generation cost of the controllable generator setThe following formula:
wherein ,the output power of the controllable generator set at the time t; a isG.i、bG,i、cG,iiIs a cost factor;
CO of the controllable generator set2Cost of emissionsThe following formula:
wherein ,dG.i、eG,i、fG,iiIs a discharge cost factor;
charge and discharge benefits of the stored energyThe following formula:
wherein, delta is the charging and discharging state of energy storage, 0 represents energy storage discharging, 1 represents energy storage charging,to charge the power for the stored energy,for storing discharge power, pitThe electricity price at the time t is, and delta t is the duration of each time interval;
charge fee of the flexible loadThe following formula:
wherein ,charging power to the flexible load.
Further, the energy and power constraints of the stored energy include: charging and discharging equality constraint of energy storage, energy storage charging and discharging power constraint, energy constraint of energy storage and energy regression constraint of energy storage;
the energy storage charge-discharge equation is constrained by the following formula:
wherein ,to store the energy level at time t, δ is the charge-discharge state of the stored energy, with 0 indicating stored energy discharge, 1 indicating stored energy charge, ηchFor charging efficiency, ηdisIn order to achieve a high discharge efficiency,to charge the power for the stored energy,for the energy storage discharge power, Δ t is the duration of each time period;
the energy storage charging and discharging power constraint is as follows:
wherein ,for the maximum value of the stored energy charging power,the maximum value of the energy storage discharge power;
the energy constraint of the stored energy is as follows:
wherein ,the minimum value of the energy stored is the energy,the maximum value of the stored energy;
the energy storage energy regression constraint is as follows:
wherein ,indicating the energy level at the starting moment,indicating the energy level at the end of the optimization period.
Further, the energy and power constraints of the compliant load include: the method comprises the following steps of (1) limiting the electric quantity change relationship before and after flexible load charging, limiting the charging power of the flexible load, limiting the electric quantity of a flexible load battery, and restricting the charging requirement of a flexible load user;
the relationship between the electric quantity change before and after the flexible load is charged is as follows:
wherein ,for the energy level of the compliant load at time t, ηEVIn order to achieve the charging efficiency of the flexible load,for flexible loadingCharging power, delta t is the duration of each time interval;
the flexible load charging power limit is as follows:
wherein ,maximum charging power for the flexible load;
the electric quantity limit of the flexible load battery is as follows:
wherein ,is the minimum amount of energy for the compliant load,is the energy maximum of the compliant load;
the charging demand constraints of the flexible load user are as follows:
wherein ,is the energy level when the electric automobile is connected to the micro-grid,is the energy level of the electric vehicle when it leaves the microgrid,the energy level reference value of the electric automobile.
A microgrid electrical energy safe and economic dispatch system, the system comprising:
the scheduling module is used for substituting the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a pre-established microgrid operation model to obtain an active output reference value of the adjustable resource in the microgrid within a set time scale;
the execution module is used for carrying out load flow calculation on the micro-grid based on the active power output reference value to obtain a voltage initial value of each node and checking whether each node has voltage out-of-limit or not;
and the correction module is used for circularly and iteratively correcting the active output range of the adjustable resource through a set voltage control strategy aiming at the node with the voltage out-of-limit until the voltage out-of-limit is eliminated, and obtaining the optimal active output value.
The scheduling module includes: the micro-grid operation model unit and the solving unit;
the micro-grid operation model unit is used for establishing a micro-grid operation model, and comprises a target function with the lowest total operation cost of the micro-grid controllable generator set, energy and power constraints of stored energy and power constraints of a flexible load;
the solving unit brings the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a microgrid operation model, and obtains the active output reference value of the adjustable resource in the microgrid within a set time scale through optimization solving.
The execution module comprises: a calculation unit and an inspection unit;
the calculating unit is used for carrying out load flow calculation on the micro-grid according to the active power output reference value to obtain a voltage initial value of each node;
and the checking unit is used for checking and determining the node with the voltage out-of-limit according to the initial voltage value of each node.
The correction module includes: a voltage control adjustment unit and a correction unit;
the voltage control adjusting unit is used for adjusting the active output range of the adjustable resource according to a voltage control strategy aiming at a node with voltage out-of-limit;
and the correcting unit is used for feeding back the adjusted active output range of the adjustable resource to the scheduling module as a constraint condition to perform optimization solution again until the voltage of the microgrid node is eliminated, and converging the objective function with the lowest total operation cost of the microgrid controllable generator set to an optimal solution.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a safe and economic dispatching method for electric energy of a microgrid, which is characterized in that adjustable resource operation data in the microgrid are substituted into a microgrid operation model which is established in advance, and an active output reference value of adjustable resources in the microgrid within a set time scale is obtained through optimization solution according to renewable energy prediction data and load prediction data which are collected in advance; performing load flow calculation on the micro-grid based on the active power output reference value, the pre-collected renewable energy source prediction data and the load prediction data to obtain a voltage initial value of each node, and determining a node where voltage out-of-limit occurs according to the voltage initial value of each node; and correcting the active output range of the adjustable resource by a preset voltage control strategy aiming at the node with the voltage out-of-limit, feeding the corrected active output range of the adjustable resource as a constraint condition back to the microgrid operation model for optimizing solution again until the voltage out-of-limit is eliminated, and obtaining the optimal active output value. According to the technical scheme provided by the invention, the active output of the adjustable resource in the microgrid is eliminated and adjusted by combining a voltage control strategy through a microgrid operation model reflecting the total operation cost of the microgrid controllable generator set, so that the optimization of the active output of the adjustable resource is realized while the economic benefit and the safe operation are considered.
The technical scheme provided by the invention provides a new voltage control strategy, the control strategy realizes the closed-loop correction of the node voltage, and the economic operation of a micro-grid is promoted while the system safety is ensured.
Drawings
FIG. 1 is a flow chart of a safe and economic dispatching method for microgrid electric energy according to the present invention;
fig. 2 is a flowchart illustrating an embodiment of a method for safe and economic dispatching of microgrid power;
FIG. 3 is a diagram of a hierarchical control architecture for a microgrid according to an embodiment of the present invention;
FIG. 4 is a flow chart of a voltage control strategy taken in an embodiment of the present invention;
FIG. 5 is a diagram of a microgrid system in an embodiment of the present invention;
fig. 6 is a comparison graph of results of node voltage amplitudes before and after optimization by using the method for safe and economic dispatching of microgrid electric energy according to the embodiment of the present invention;
fig. 7 is a schematic structural diagram of a microgrid power energy safe and economic dispatching system of the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Example 1:
the embodiment of the invention provides a safe and economic dispatching method for microgrid electric energy, which is implemented in a specific process as shown in fig. 1 and comprises the following steps:
s101: the method comprises the steps of substituting adjustable resource operation data in the microgrid into a microgrid operation model which is established in advance, and obtaining an active output reference value of adjustable resources in the microgrid within a set time scale through optimization solution according to renewable energy source prediction data and load prediction data which are collected in advance;
s102: carrying out load flow calculation on the micro-grid based on the active power output reference value, the pre-collected renewable energy source prediction data and the load prediction data to obtain a voltage initial value of each node, and determining a node with voltage out-of-limit according to the voltage initial value of each node;
s103: and correcting the active output range of the adjustable resource by a preset voltage control strategy aiming at the node with the voltage out-of-limit, feeding the corrected active output range of the adjustable resource as a constraint condition back to the microgrid operation model for optimization solution again until the voltage out-of-limit is eliminated, and obtaining the optimal active output value.
Specifically, in the implementation process, the microgrid control architecture is divided into a scheduling layer, an execution layer and a correction layer, and optimal scheduling of microgrid power is realized through hierarchical control, as shown in fig. 2 and 3.
Step S101, bringing adjustable resource operation data in the microgrid into a microgrid operation model which is established in advance, and obtaining an active output reference value of the adjustable resource in the microgrid within a set time scale through optimization and solution according to renewable energy source prediction data and load prediction data which are collected in advance, wherein the active output reference value specifically comprises the following steps:
step S101-1, as shown in fig. 2, obtaining the predicted power of the renewable energy and the load;
step S101-2, considering economic and environmental benefits, establishing controllable generator setCost model and CO2The discharge model, the charge and discharge benefits of the stored energy and the charge cost of the flexible load are respectively shown as a formula (1), a formula (2), a formula (3) and a formula (4);
in the formula,the power generation cost of the controllable generator set;CO for controllable generator sets2Discharging cost;the output power of the controllable generator set at the time t; a isG,i、bG,i、CG,iRespectively are cost coefficients; dG,i、 eG,i、fG,iRespectively, the emission cost coefficients; delta is the charge-discharge state of the stored energy, 0 represents the stored energy discharge, 1 represents the stored energy charge,to charge the power for the stored energy,for storing discharge power, pitIs the electricity price at the time of the t,charging power for the flexible load;
s101-3, constructing a total operation cost function of the microgrid;
in the formula,CtotalThe total day-ahead operation cost of the micro-grid is obtained; t, NGenRespectively optimizing the total time interval number of scheduling and the total number of controllable generator sets;
and S101-4, respectively establishing mathematical models of the energy storage vehicle and the electric vehicle according to formulas (6) to (9) and formulas (10) to (13). On the basis, the active output of the adjustable resources is taken as a control variable, and the active output reference value of every 15min before the day is calculated;
equation (6) is the charging and discharging equality constraint of the stored energy, wherein,representing the energy level of the stored energy at the time t, delta being a variable from 0 to 1 and representing the charging and discharging states of the stored energy, 0 representing the stored energy discharging and 1 representing the stored energy charging, ηch、ηdisRespectively charge and discharge efficiency;charging and discharging power for energy storage; Δ t represents the duration of each period; formula (7) is energy storage charging and discharging power constraint; formula (8) is the energy constraint of the stored energy; equation (9) is the energy regression constraint for stored energy,andrespectively representing the energy levels of the starting moment and the optimization end period;
the expressions (10) to (13) have similar meanings to the expressions (6) to (9), and are not described herein in detail. Equation (13) is a charging demand constraint for an electric vehicle user, wherein,respectively the energy level when the electric automobile is connected into the micro-grid and leaves the micro-grid,the electric quantity level required by the user after the charging is finished;
specifically, step S103 corrects the active output range of the adjustable resource through a preset voltage control strategy for the node where the voltage is out-of-limit, and feeds back the corrected active output range of the adjustable resource as a constraint condition to the microgrid operation model for optimization solution again until the voltage is out-of-limit eliminated and the optimal active output value is obtained; the voltage control strategy flowchart is shown in fig. 4, and specifically includes:
step S103-1, aiming at the node where the voltage out-of-limit occurs, adopting the voltage control strategies described in the formulas (14) to (21) to correct the active output range of the adjustable resource;
Ij,t＝λjΔVj(18)
the expression (14) represents a network matrix N, wherein the elements reflect the causative degree of voltage out-of-limit of a controllable physical unit (namely, an adjustable resource) in the microgrid to a certain node, and the causative degree is a positive value and has the size of NUnit×NNode， NUnit、NNodeRespectively the total number of the controllable units and the total number of the nodes; the concrete expression of network matrix element is given by formula (15) and formula (16), LijIs the line length between controllable element i and node j. When the voltage threshold is exceeded at the node connected to a controllable unit, Ni,jThe value is 1, and the values of network matrix elements corresponding to other controllable units in the microgrid are 0;
equation (17) represents an indication matrix I indicating where and when the voltage violation occurs; the formula (18) and the formula (19) are the concrete expressions of the elements in the formula I, and lambdajIs a variable from 0 to 1, and when the voltage of the node j exceeds the limit, lambdajThe value is 1; otherwise, λjThe value is 0;is the nominal voltage of node j;
equation (20) is a calculation equation of dynamic gain, Ai,tReflecting the level of each controllable unit for adjusting the self-output range in order to eliminate the voltage out-of-limit; the formula (21) gives a specific adjustment mode: when low voltage occurs, the lower limit of the output force of the controllable unit is increased; when overvoltage occurs, reducing the upper limit of the output of the controllable unit;
and S103-2, repeating the step S101-4 to the step S103-1 until the voltage threshold is eliminated and the target function converges to an optimal solution.
Example 2:
in the embodiment of the invention, an IEEE 33 node power distribution system is adopted to simulate a microgrid structure, as shown in fig. 5. The access positions of 2 micro gas turbines are nodes 2 and 8, and the rated capacities are 80 kW and 55kW respectively; 1 fuel cell is connected with a node 24, and the rated capacity is 60 kW; the access positions of the fan and the photovoltaic are respectively nodes 27 and 30, and the rated capacity is 30 kW; the energy storage access position is a node 16, and the rated capacity is 200 kWh; the 2 electric automobiles are respectively connected to the nodes 20 and 32, the battery capacity is 32kWh, and the rated charging power is 7 kW. The following explains the simulation results of the embodiment of the present invention:
as can be seen from fig. 6, after the method provided by the present invention is used for microgrid electric energy scheduling, the voltage amplitude of the system node is greatly increased, the average value of the voltage amplitude is increased from 0.9453 before optimization to 0.9760 after optimization, and the node voltage distribution of the system is effectively improved without the occurrence of the condition that the node voltage is out of limit. Meanwhile, before and after the micro-grid power optimization scheduling method provided by the invention is adopted, the daily operation cost of the micro-grid is 745.69 yuan and 768.30 yuan respectively. Therefore, after the node voltage constraint is considered, although the optimal operation cost of the microgrid is degraded to a certain extent, the cost is not increased greatly, and in addition, by means of the voltage control strategy, the node voltage distribution of the system can be obviously improved.
Example 3:
based on the same inventive concept, the invention also provides a microgrid electric energy safe and economic dispatching system, the system structure diagram of which is shown in fig. 7, the system comprises:
the system comprises:
the scheduling module is used for substituting the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a pre-established microgrid operation model to obtain an active output reference value of the adjustable resource in the microgrid within a set time scale;
the execution module is used for carrying out load flow calculation on the micro-grid based on the active power output reference value to obtain a voltage initial value of each node and checking whether each node has voltage out-of-limit or not;
and the correction module is used for circularly and iteratively correcting the active output range of the adjustable resource through a set voltage control strategy aiming at the node with the voltage out-of-limit until the voltage out-of-limit is eliminated, and obtaining the optimal active output value.
The scheduling module includes: the micro-grid operation model unit and the solving unit;
the micro-grid operation model unit is used for establishing a micro-grid operation model, and comprises a target function with the lowest total operation cost of the micro-grid controllable generator set, energy and power constraints of stored energy and power constraints of a flexible load;
the solving unit brings the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a microgrid operation model, and obtains the active output reference value of the adjustable resource in the microgrid within a set time scale through optimization solving.
The execution module comprises: a calculation unit and an inspection unit;
the calculating unit is used for carrying out load flow calculation on the micro-grid according to the active power output reference value to obtain a voltage initial value of each node;
and the checking unit is used for checking and determining the node with the voltage out-of-limit according to the initial voltage value of each node.
The correction module includes: a voltage control adjustment unit and a correction unit;
the voltage control adjusting unit is used for adjusting the active output range of the adjustable resource according to a voltage control strategy aiming at a node with voltage out-of-limit;
and the correcting unit is used for feeding back the adjusted active output range of the adjustable resource to the scheduling module as a constraint condition to perform optimization solution again until the voltage of the microgrid node is eliminated, and converging the objective function with the lowest total operation cost of the microgrid controllable generator set to an optimal solution.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (17)
1. A safe and economic dispatching method for electric energy of a micro-grid is characterized by comprising the following steps:
the method comprises the steps of substituting adjustable resource operation data in the microgrid into a microgrid operation model which is established in advance, and obtaining an active output reference value of adjustable resources in the microgrid within a set time scale through optimization solution according to renewable energy source prediction data and load prediction data which are collected in advance;
performing load flow calculation on the micro-grid based on the active power output reference value, the pre-collected renewable energy source prediction data and the load prediction data to obtain a voltage initial value of each node, and determining a node where voltage out-of-limit occurs according to the voltage initial value of each node;
correcting the active output range of the adjustable resource by a preset voltage control strategy aiming at a node with voltage out-of-limit, feeding back the corrected active output range of the adjustable resource to the microgrid operation model as a constraint condition, and performing optimization solution again until the voltage out-of-limit is eliminated and the optimal active output value is obtained;
the adjustable resources in the microgrid comprise: controllable generating set, energy storage and flexible load.
2. The microgrid electrical energy safe and economic dispatching method of claim 1, wherein the modifying the active output range of the adjustable resource through a preset voltage control strategy for the node where the voltage violation occurs comprises:
based on the node with the out-of-limit generated voltage, establishing a network matrix of the out-of-limit generated voltage cause degree of the adjustable resource node in the micro-grid and an indication matrix indicating the out-of-limit generated position and the generated moment of the adjustable resource node voltage in the micro-grid;
multiplying the network matrix and the indication matrix to obtain a dynamic gain matrix which reflects that each adjustable resource in the micro-grid adjusts the level of the self output range in order to eliminate the voltage out-of-limit;
and correcting the active output range of the adjustable resources in the microgrid according to the dynamic gain matrix.
3. The microgrid electrical energy safe and economic dispatching method of claim 2,
the network matrix is as follows:
wherein ,Ni,jThe size of the cause of voltage out-of-limit on the node j for the ith adjustable resource, NUnitTo adjust the total number of resources, NNodeIs the total number of nodes;
the indication matrix is:
wherein ,Ij,tAnd the voltage change rate of the node j when the voltage exceeds the threshold at the time T is shown, and T is the total time period number of the optimized scheduling.
4. The microgrid electrical energy safe and economic dispatching method of claim 3, characterized in that the size N of the cause of voltage violation of node j generated by the ith adjustable resourcei,jIs determined by the following formula:
wherein ,LijIs the length of the line between resource i and node j can be adjusted.
5. The microgrid electric energy safe and economic dispatching method of claim 3,
rate of change of voltage I at node j when voltage overshoot occurs at time tj,tThe following formula:
Ij,t＝λjΔVj
wherein ,λjThe voltage threshold-crossing parameter is a variable 0/1, and when the voltage threshold-crossing occurs at the node j, lambda isjA value of 1, otherwise, λjThe value is 0; Δ VjIs the rate of change of voltage.
6. The microgrid electric energy safe and economic dispatching method of claim 5,
the voltage change rate DeltaVjThe following formula:
wherein ,is the rated voltage of node j, VjAnd calculating the initial voltage value of the node j for the load flow.
7. The microgrid electric energy safe and economic dispatching method of claim 3,
the dynamic gain matrix is:
wherein ,Ai,tThe level of the self-output range is adjusted for each adjustable resource in order to eliminate voltage violations.
8. The microgrid energy safe and economic dispatching method of claim 7, wherein the active output range of the tunable resources is modified by the following formula:
wherein ,is the rated upper limit of the output of the adjustable resource i,is the rated lower output limit of the adjustable resource i,the minimum power that can be emitted at time t after the output is adjusted for the adjustable resource i,and adjusting the maximum power which can be emitted at the time t after the output is performed on the adjustable resource i.
9. The microgrid electric energy safe and economic dispatching method of claim 1, wherein the establishment of the microgrid operation model comprises:
according to the adjustable resource operation data in the microgrid, the economic and environmental benefits are calculated, and the cost function and the CO of the controllable generator set of the microgrid are established2The discharge function, the charge and discharge benefits of the stored energy and the charge cost of the flexible load;
cost function based on controllable generator set, CO of controllable generator set2Determining a target function with the lowest total operation cost of the micro-grid controllable generator set according to the discharge function, the charge-discharge income of stored energy and the charge cost of the flexible load;
determining the rated upper and lower output limits of the controllable generator set as the initial constraint of the output of the controllable generator set according to the operation data of the controllable generator set;
and determining energy and power constraint of the stored energy and power constraint of the flexible load according to the charging and discharging characteristics of the stored energy and the flexible load.
10. The microgrid electric energy safe and economic dispatching method of claim 9, characterized in that an objective function for minimizing the total operating cost of the microgrid controllable generator set is as follows:
wherein ,CtotalFor the total day-ahead operating cost of the micro-grid,in order to control the power generation cost of the generator set,CO for controllable generator sets2The cost of the discharge is high,for the charging and discharging benefit of the stored energy,charging cost for flexible load, T is total time period number of optimized scheduling, NGenThe total number of the controllable generator sets.
11. The microgrid electric energy safe and economic dispatching method of claim 10,
generating cost of the controllable generator setThe following formula:
wherein ,the output power of the controllable generator set at the time t; a isG.i、bG,i、cG,iiIs a cost factor;
CO of the controllable generator set2Cost of emissionsThe following formula:
wherein ,dG.i、eG,i、fG,iiIs a discharge cost factor;
charge and discharge benefits of the stored energyThe following formula:
wherein, delta is the charging and discharging state of energy storage, 0 represents energy storage discharging, 1 represents energy storage charging,to charge the power for the stored energy,for storing discharge power, pitThe electricity price at the time t is, and delta t is the duration of each time interval;
charge fee of the flexible loadThe following formula:
wherein ,charging power to the flexible load.
12. The microgrid electrical energy safe and economic dispatching method of claim 10, wherein the stored energy and power constraints comprise: charging and discharging equality constraint of energy storage, energy storage charging and discharging power constraint, energy constraint of energy storage and energy regression constraint of energy storage;
the energy storage charge-discharge equation is constrained by the following formula:
wherein ,to store the energy level at time t, δ is the charge-discharge state of the stored energy, with 0 indicating stored energy discharge, 1 indicating stored energy charge, ηchFor charging efficiency, ηdisIn order to achieve a high discharge efficiency,to charge the power for the stored energy,for the energy storage discharge power, Δ t is the duration of each time period;
the energy storage charging and discharging power constraint is as follows:
wherein ,for the maximum value of the stored energy charging power,the maximum value of the energy storage discharge power;
the energy constraint of the stored energy is as follows:
wherein ,the minimum value of the energy stored is the energy,the maximum value of the stored energy;
the energy storage energy regression constraint is as follows:
wherein ,indicating the energy level at the starting moment,indicating the energy level at the end of the optimization period.
13. The microgrid energy safe and economic dispatching method of claim 10, wherein the energy and power constraints of the flexible loads comprise: the method comprises the following steps of (1) limiting the electric quantity change relationship before and after flexible load charging, limiting the charging power of the flexible load, limiting the electric quantity of a flexible load battery, and restricting the charging requirement of a flexible load user;
the relationship between the electric quantity change before and after the flexible load is charged is as follows:
wherein ,for the energy level of the compliant load at time t, ηEVIn order to achieve the charging efficiency of the flexible load,charging power for the flexible load, wherein delta t is the duration of each time interval;
the flexible load charging power limit is as follows:
wherein ,maximum charging power for the flexible load;
the electric quantity limit of the flexible load battery is as follows:
wherein ,is the minimum amount of energy for the compliant load,is the energy maximum of the compliant load;
the charging demand constraints of the flexible load user are as follows:
wherein ,is the energy level when the electric automobile is connected to the micro-grid,is the energy level of the electric vehicle when it leaves the microgrid,the energy level reference value of the electric automobile.
14. A microgrid electrical energy safe and economic dispatch system, the system comprising:
the scheduling module is used for substituting the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a preset microgrid operation model to obtain an active output reference value of the adjustable resource in the microgrid within a set time scale;
the execution module is used for carrying out load flow calculation on the micro-grid based on the active power output reference value to obtain a voltage initial value of each node and checking whether each node has voltage out-of-limit or not;
and the correction module is used for circularly and iteratively correcting the active output range of the adjustable resource through a set voltage control strategy aiming at the node with the voltage out-of-limit until the voltage out-of-limit is eliminated and the optimal active output value is obtained.
15. The microgrid electrical energy safe and economic dispatch system of claim 14, wherein the dispatch module comprises: the micro-grid operation model unit and the solving unit;
the micro-grid operation model unit is used for establishing a micro-grid operation model, and comprises a target function with the lowest total operation cost of the micro-grid controllable generator set, energy and power constraints of stored energy and power constraints of a flexible load;
the solving unit brings the adjustable resource operation data, the renewable energy source prediction data and the load prediction data in the microgrid into a microgrid operation model, and obtains the active output reference value of the adjustable resource in the microgrid within a set time scale through optimization solving.
16. The microgrid electrical energy safe and economic dispatch system of claim 14, wherein the execution module comprises: a calculation unit and an inspection unit;
the calculating unit is used for carrying out load flow calculation on the micro-grid according to the active power output reference value to obtain a voltage initial value of each node;
and the checking unit is used for checking and determining the node with the voltage out-of-limit according to the initial voltage value of each node.
17. The microgrid electrical energy safe and economic dispatch system of claim 14, wherein the correction module comprises: a voltage control adjustment unit and a correction unit;
the voltage control adjusting unit is used for adjusting the active output range of the adjustable resource according to a voltage control strategy aiming at a node with voltage out-of-limit;
and the correcting unit is used for feeding back the adjusted active output range of the adjustable resource to the scheduling module as a constraint condition to perform optimization solution again until the voltage of the microgrid node is eliminated, and converging the objective function with the lowest total running cost of the microgrid controllable generator set to an optimal solution.
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| CN111023257A (en) * | 2019-12-30 | 2020-04-17 | 国网北京市电力公司 | Control method and device of electric heating equipment, storage medium and processor |
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| CN112670978A (en) * | 2020-12-14 | 2021-04-16 | 贵州万峰电力股份有限公司 | Power grid operation optimization method and system |
| CN112670978B (en) * | 2020-12-14 | 2023-11-21 | 贵州万峰电力股份有限公司 | Power grid operation optimization method and system |
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