CN113496439A - Direct current power flow model optimization method and system considering network loss - Google Patents

Direct current power flow model optimization method and system considering network loss Download PDF

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CN113496439A
CN113496439A CN202110664943.4A CN202110664943A CN113496439A CN 113496439 A CN113496439 A CN 113496439A CN 202110664943 A CN202110664943 A CN 202110664943A CN 113496439 A CN113496439 A CN 113496439A
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白杨
陈中飞
宋慧
王龙
于鹏
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Guangdong Power Grid Co Ltd
Electric Power Dispatch Control Center of Guangdong Power Grid Co Ltd
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Abstract

The invention discloses a direct current power flow model optimization method considering network loss, and belongs to the field of electrical engineering. The method is based on the original alternating current power flow model, combines with the existing widely used direct current power flow model, and carries out approximate assumption and mathematical transformation on the former to obtain a model which is simpler and more accurate than the former. The model considers factors such as actual voltage, phase angle, network topology, line conductance and the like, and then combines the initial condition to correct the network loss of the original direct current power flow, so as to finally obtain the power flow of each branch in the network. The invention provides a new idea for the power flow scheduling in the power market, is beneficial to safety check and margin analysis, and ensures the stability of the operation of the power system.

Description

Direct current power flow model optimization method and system considering network loss
Technical Field
The invention relates to the technical field of electrical engineering, in particular to a direct current power flow model optimization method and system considering network loss.
Background
The spot market reform is gradually implemented in China, the original scheduling mode of a power grid is changed by the spot market reform, and the combination of safety constraint units and the safety constraint economic scheduling in the day-ahead market and the real-time market become an important ring.
However, from the test run results of part of the current regions, the alternating current power flow model is adopted, the solving speed is too slow, or the direct current power flow model is adopted, and the precision is difficult to improve.
Disclosure of Invention
The invention provides a direct current power flow model optimization method and system considering network loss, and aims to solve the problems that the existing alternating current power flow method is too slow in calculation and inaccurate in direct current power flow, so that the calculation amount is greatly reduced while the calculation accuracy is improved.
The invention provides a direct current power flow model optimization method considering network loss in a first aspect, which comprises the following steps:
on the basis of an alternating current power flow calculation model, when the change values of a phase angle and voltage are determined to be smaller than preset values, similarity processing is carried out on the calculation of the phase angle and the voltage in the alternating current power flow calculation model, and square reduction processing is carried out on the high-order side calculation of the phase angle and the voltage, so that a simplified alternating current power flow model is obtained; wherein the similarity process is a simplification of the calculations regarding phase angle and voltage; the square reduction processing is to change the high-order calculation into low-order calculation through Taylor expansion;
and on the basis of the simplified alternating current power flow model, replacing a voltage phase angle variable with a system initial value to obtain a direct current power flow model considering the network loss.
Further, before replacing the voltage and phase angle variables with the system initial values, the method further includes:
and determining a loss factor according to the function quantity of the voltage in the simplified alternating current power flow model related to the initial value of the phase angle.
Further, when it is determined that the variation values of the phase angle and the voltage are smaller than the preset values on the basis of the alternating current power flow calculation model, performing similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model and performing square reduction processing on the high-order calculation of the phase angle and the voltage to obtain a simplified alternating current power flow model, including:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure BDA0003116458270000021
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000022
vivjθij≈θij；
Figure BDA0003116458270000023
wherein v isi，0，vj，0Representing the initials of node i and node j, respectivelyA state voltage amplitude;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000031
Figure BDA0003116458270000032
wherein, thetaij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
Further, the simplified alternating current power flow model is as follows:
Figure BDA0003116458270000033
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the phase angles of the voltages at the initial states of node i and node j, vi，0，vj，0Representing the initial state voltage magnitudes at node i and node j, respectively.
Further, on the basis of the simplified alternating current power flow model, a system initial value is used for replacing a voltage and a phase angle variable, and the calculation is carried out through the following formula:
Figure BDA0003116458270000034
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase between node i and node jAngular difference, bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; v. ofi，0，vj，0Representing the initial state voltage magnitudes of node i and node j, respectively.
Further, the loss factor is calculated by the following formula:
Figure BDA0003116458270000035
wherein, CθIs a constant number of angles, CviAnd CvjIs the constant number of voltages, θ, at node i and node j, respectivelyij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
Further, the direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting the phase angle difference between node i and node j, b representing the susceptance on the line, and L representing the loss factor.
The second aspect of the present invention provides a dc power flow model optimization system considering network loss, including:
the numerical value processing module is used for carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model and carrying out square reduction processing on the calculation of the high-order side of the phase angle and the voltage when the change values of the phase angle and the voltage are determined to be smaller than a preset value on the basis of the alternating current power flow calculation model to obtain a simplified alternating current power flow model; wherein the similarity processing is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change the high-order calculation into low-order calculation through Taylor expansion;
and the network loss reference module is used for replacing voltage and phase angle variables by using the system initial value on the basis of simplifying the alternating current power flow model to obtain the direct current power flow model considering network loss.
Further, the dc power flow model optimization system considering the network loss further includes:
and the loss factor determining module is used for determining the loss factor according to the function quantity of the voltage in the simplified alternating current power flow model related to the initial value of the phase angle.
Further, when it is determined that the variation values of the phase angle and the voltage are smaller than the preset values on the basis of the alternating current power flow calculation model, performing similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model and performing square reduction processing on the high-order calculation of the phase angle and the voltage to obtain a simplified alternating current power flow model, including:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure BDA0003116458270000051
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000052
vivjθij≈θij；
Figure BDA0003116458270000053
wherein v isi，0，vj，0Respectively show the sectionsInitial state voltage amplitudes at point i and node j;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000054
Figure BDA0003116458270000055
wherein, thetaij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained;
the simplified alternating current power flow model comprises the following steps:
Figure BDA0003116458270000056
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the phase angles of the voltages at the initial states of node i and node j, vi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
on the basis of the simplified alternating current power flow model, the initial value of the system is used for replacing voltage and phase angle variables, and the calculation is carried out through the following formula:
Figure BDA0003116458270000061
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j，bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; v. ofi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
the loss factor is calculated by the following formula:
Figure BDA0003116458270000062
wherein, CθIs a constant number of angles, CviAnd CvjIs the constant number of voltages, θ, at node i and node j, respectivelyij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained;
the direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting the phase angle difference between node i and node j, b representing the susceptance on the line, and L representing the loss factor.
Compared with the prior art, the embodiment of the invention has the beneficial effects that:
the invention provides a direct current power flow model optimization method and system considering network loss, wherein the method comprises the following steps: on the basis of an alternating current power flow calculation model, when the change values of phase angles and voltages are determined to be smaller than preset values, similarity processing is carried out on the calculation of the phase angles and the voltages in the alternating current power flow calculation model, and the high-order side calculation of the phase angles and the voltages is carried out to reduce the side, so that a simplified alternating current power flow model is obtained; wherein the similarity process is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change high-order square calculation into low-order square calculation through Taylor expansion; and on the basis of the simplified alternating current power flow model, replacing a voltage phase angle variable with a system initial value to obtain a direct current power flow model considering the network loss. Compared with alternating current solution, the method can greatly save calculation time, and can effectively improve the efficiency compared with direct current power flowCalculating the precision, and taking the direct current power flow model of the network loss into consideration as P ═ b thetaijAnd the method considers a correction term L with network loss, thereby improving the calculation precision of the power flow. Therefore, the efficiency and the reliability in the scheduling process can be improved.
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In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a dc power flow model optimization considering network loss according to an embodiment of the present invention
Fig. 2 is a diagram of an apparatus of a dc power flow model optimization system considering network loss according to an embodiment of the present invention;
fig. 3 is a block diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. 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.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.
From the test run results of partial areas at present, the solution speed is too slow by adopting an alternating current power flow model, or the accuracy is difficult to improve by adopting a direct current power flow model. Therefore, in order to improve the accuracy of the line load flow and ensure that the calculation amount is not increased, a method for calculating the load flow by reasonably considering the network loss is urgently needed, the operating abundance and the operating reliability of the power market scheduling operation after the transformation of the power grid are maintained, and the normal operation of the society is ensured.
Aiming at the defects of the prior art, the invention aims to provide a direct current power flow model optimization considering network loss, and aims to solve the problems that the existing alternating current power flow method is too slow in calculation and inaccurate in direct current power flow, so that the calculation amount is greatly reduced while the calculation accuracy is improved.
The direct current power flow model considering the network loss can be applied to real-time market direct current power flow dispatching clearing in the existing market environment to improve the dispatching precision. In the actual power system scheduling process, load flow calculation is a necessary loop, and most of the current scheduling processes mainly adopt a direct current load flow model, so that the accuracy is not accurate and the deviation from the actual process is large. The method corrects the power flow, enables calculation to be more fit to actual conditions in direct current power flow optimization scheduling, and can solve some scheduling conditions which cannot be solved before after the constraint of the line capacity is reduced, so that the scheduling operation condition of the power grid is effectively improved.
A first aspect.
Referring to fig. 1, an embodiment of the present invention provides a method for optimizing a dc power flow model considering network loss, including:
s10, on the basis of the alternating current power flow calculation model, when the change values of the phase angle and the voltage are determined to be smaller than preset values, similarity processing is carried out on the calculation of the phase angle and the voltage in the alternating current power flow calculation model, and power reduction processing is carried out on the calculation of the high-order power of the phase angle and the voltage, so that a simplified alternating current power flow model is obtained; wherein the similarity process is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change the high-order square calculation into low-order square calculation through Taylor expansion.
In a specific embodiment, the step S10 includes:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure BDA0003116458270000091
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000092
vivjθij≈θij；
Figure BDA0003116458270000101
wherein v isi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000102
Figure BDA0003116458270000103
wherein, thetaij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
The direct current power flow model is as follows:
Figure BDA0003116458270000104
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, upsilon, on a line between node i and node ji，υjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the voltage phase angles at node i and node j in the initial state, upsiloni，0，υi，0Representing the initial state voltage magnitudes at node i and node j, respectively.
And S20, determining the loss factor according to the function quantity of the voltage in the simplified alternating current power flow model and the phase angle initial value.
In one embodiment, the loss factor is calculated by the following formula:
Figure BDA0003116458270000111
wherein, CθIs a constant number of angles, CviAnd CvjAre node i and node j, respectivelyConstant amount of voltage of (a) (-)ij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
And S30, replacing the voltage phase angle variable with the system initial value on the basis of the simplified alternating current power flow model to obtain a direct current power flow model considering the network loss.
In a specific embodiment, on the basis of the simplified ac power flow model, the system initial value is used to replace the voltage and phase angle variables, and the calculation is performed by the following formula:
Figure BDA0003116458270000112
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; v. ofi，0，vj，0Representing the initial state voltage magnitudes of node i and node j, respectively.
The direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting the phase angle difference between node i and node j, b representing the susceptance on the line, and L representing the loss factor.
In a specific embodiment, the present invention provides, on the one hand, a method for optimizing a dc power flow model considering network loss, and the specific contents are as follows:
the alternating current power flow model is widely applied to various power system analysis and can be expressed as the following formula:
Figure BDA0003116458270000113
wherein P isijIndicating presence of a line between node i and node jWork power, θijRepresents the phase angle difference between node i and node j, gijRepresenting the value of the electrical conductivity on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage magnitudes at node i and node j, respectively. After the actual power system network topology is determined, the conductance, susceptance values of the lines are determined, and when a system begins to operate in power flow, the voltage and phase angle values may be obtained by using a computer or power flow solving software, such as matpower, Matacdc, etc. The formula is suitable for the condition of a single line with two connected nodes, and if a plurality of lines are connected, parallel processing is required.
In actual power system operation, the variation fluctuation of the phase angle and the voltage is small, so the following assumptions can be made:
Figure BDA0003116458270000121
vivjθij≈θij (3)
in addition, considering that under the actual power grid operating environment, taking real-time market scheduling as an example, when the power grid has only slight load fluctuation compared with the voltage amplitude under the basic condition, the actual variation of the voltage is very small in one real-time scheduling time period every 15 minutes, and can be approximately considered as not changing compared with the previous time period, so that the voltage expression can be further processed in an approximate manner:
Figure BDA0003116458270000122
wherein v isi，0，vj，0Representing the initial state voltage amplitudes, v, of nodes i and j, respectivelyijRepresenting the difference in voltage magnitude between node i and node j. Taking real-time market scheduling as an example, the initial state voltage amplitude can be selected from parameters solved by the computer in the last time period and substituted into the calculation in the current time periodAnd (5) performing line iteration processing. The difference of the voltage amplitudes is obtained by solving the current in the current period. And (3) substituting the expressions (2), (3) and (4) into the expression (1) to obtain a preliminarily simplified alternating current power flow model.
However, these approximations are not enough, the voltage and the phase angle are still in the high power state, and the linearization should be ensured as much as possible, so that the voltage and the phase angle are subjected to taylor expansion, and the following two steps are respectively carried out:
Figure BDA0003116458270000131
Figure BDA0003116458270000132
wherein theta isij，0Is the difference between the voltage phase angles at the initial states of node i and node j. Similar to the amplitude of the initial state voltage, the difference between the phase angles of the initial state voltage can also be selected from parameters solved by the computer in the previous time period and substituted into the calculation solution in the time period for iterative processing. And then, continuously substituting the equations (5) and (6) into the equation (1) for arrangement, so as to obtain the following tidal flow model:
Figure BDA0003116458270000133
although this is a simplified model of communication, it is still very complex. The voltage unknown quantity and the angle unknown quantity are contained, 2 variables are generated in iterative solution, and the voltage is quadratic quantity, so that great trouble is caused to calculation. Therefore, based on the equation (7), by performing a one-step approximation process to treat the voltage variable as a known quantity while ignoring the conductance in the angular expression, the following result can be obtained:
Figure BDA0003116458270000134
wherein upsilon isi，0，υi，0Voltage values, theta, representing the initial moments of nodes i and jij，0，θij，0Representing the phase angle values at the initial time of node i and node j. Observing equation (8), it can be seen that the line power flow is composed of two parts, one part is composed of the angle difference between two nodes and is a typical dc power flow model, and the other part is an additional function quantity related to the initial value of the voltage and the angle, and according to the operation experience, once the initial value is determined, or the state is determined, the part is a constant which does not need to be calculated. Thus, we shall not consider the function as multiplying it by a parameter on the original basis, and record the whole part as the loss factor L, i.e. (the equations (8) (9) have been modified due to the error of the previous expression)
Figure BDA0003116458270000141
Wherein C isθAnd CvThe constant quantities in front of the angle and the voltage variable can be corrected through an actual power flow model and also can be simplified through a formula (7), and thetaij，0Is the difference between the voltage phase angles at the initial states of node i and node j. Therefore, based on the two formulas (8) and (9), the idea of solving the power flow model after improvement can be clarified, namely, the model solution of the direct current power flow is firstly carried out, and then the network loss correction is carried out according to the expression after the alternating current simplification, the loss factor only needs to be calculated according to the existing state quantity without participating in iterative solution, so the complexity is greatly reduced, and the accuracy of the loss factor is very close to that of the direct solution of the alternating current power flow because the load fluctuation change is very small and the amplitude and phase angle fluctuation are not too large basically when a large power grid runs. Therefore, the formula (8) meets the problem that the calculated amount is not too large under the condition of ensuring the accuracy improvement of the power flow, and the formula is an improved direct-current power flow model considering the network loss. The final given line tidal flow expression is as follows:
P＝-bθij+L (10)
equation (10) is an improved dc power flow model taking the network loss into account. (Once the calculation scheme is determined, the L parameter in the model is completely handed over to computer tidal current solving software in actual scheduling, and the solution at the next moment is replaced by using the result of the previous solution so as to achieve the effect of iterative calculation.)
In another embodiment of the present invention, IEEE standard node case 39 is used for performing analysis and calculation, and example analysis is performed, and the calculation results of power flow under 3 solutions will be given below, which are the direct current power flow solution built in Matpower, the alternating current power flow solution built in Matpower, and the improved direct current model optimization method provided by the present invention.
The active power of each branch can be calculated by using a Matpower built-in direct current and alternating current flow solution, and then compared with the result of solving by using the model provided by the invention, the active power corresponding to 46 lines can be obtained, and the specific data is shown in Table 1:
TABLE 1
Figure BDA0003116458270000151
Figure BDA0003116458270000161
Because the precision of the alternating current power flow is very high, the alternating current power flow can be defaulted to be an actual value, and therefore, whether the model is accurate or not can be observed by comparing the alternating current result with data obtained by the other two methods. Calculating the mean of the percentage errors and the variance of the percentage accuracy, the data shown in the following table can be obtained:
TABLE 2
Direct current Improved DC Exchange of electricity
Mean value of percent error 6.296569 2.856405 1
Variance of percentage precision 138.7647 23.3829 0
Wherein, the calculation formula of the percentage error mean value and the percentage precision variance is as (21) (22):
avg|(Pac-Pl)/Pac|*100 (11)
var(Pl*100/Pac) (12)
avg denotes averaging and var denotes variance. PacI.e. the result of the alternating current power flow model, PlIs a direct current or the result of modifying the direct current model. According to the results, after the improved direct current power flow model is applied, in terms of accuracy, the percentage error average value is reduced to 2.85% from the previous 6.3%, particularly, the percentage error average value is closer to the result of the alternating current power flow on each line, in terms of percentage accuracy variance, the percentage error average value is also reduced to 23.4 from the previous 138.8, the power flow distribution is more concentrated, the result dispersity is smaller, and the power flow solved by the corresponding integral model is more accurate.
A second aspect.
Referring to fig. 2, an embodiment of the invention provides a dc power flow model optimization system considering network loss, including:
the numerical value processing module 10 is configured to, on the basis of the alternating current power flow calculation model, perform similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model when it is determined that the variation values of the phase angle and the voltage are smaller than a preset value, and perform square reduction processing on the calculation of the high-order side of the phase angle and the voltage to obtain a simplified alternating current power flow model; wherein the similarity process is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change the high-order calculation into the low-order calculation through Taylor expansion.
And a loss factor determination module 20 for determining a loss factor based on the function number of the voltage in the simplified ac power flow model with respect to the initial value of the phase angle.
And the network loss reference module 30 is configured to obtain a direct current power flow model considering network loss by using the initial system value to replace the voltage angle variable on the basis of the simplified alternating current power flow model.
In a specific embodiment, when it is determined that the variation values of the phase angle and the voltage are smaller than the preset values on the basis of the ac power flow calculation model, performing similarity processing on the calculation of the phase angle and the voltage in the ac power flow calculation model and performing power reduction processing on the high-order calculation of the phase angle and the voltage to obtain a simplified ac power flow model, includes:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure BDA0003116458270000181
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000182
vivjθij≈θij；
Figure BDA0003116458270000183
wherein upsilon isi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure BDA0003116458270000191
Figure BDA0003116458270000192
wherein, thetaij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained;
the simplified alternating current power flow model comprises the following steps:
Figure BDA0003116458270000193
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the phase angles of the voltages at the initial states of node i and node j, vi，0，vj，0Respectively represent nodes i andthe initial state voltage magnitude of node j;
on the basis of the simplified alternating current power flow model, the initial value of the system is used for replacing voltage and phase angle variables, and the calculation is carried out through the following formula:
Figure BDA0003116458270000194
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; upsilon isi，0，υi，0Respectively representing the initial state voltage amplitude of the node i and the node j;
the loss factor is calculated by the following formula:
Figure BDA0003116458270000201
wherein, CθIs a constant number of angles, CviAnd CvjIs the constant number of voltages, θ, at node i and node j, respectivelyij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained;
the direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting the phase angle difference between node i and node j, b representing the susceptance on the line, and L representing the loss factor.
In a third aspect.
The present invention provides an electronic device, including:
a processor, a memory, and a bus;
the bus is used for connecting the processor and the memory;
the memory is used for storing operation instructions;
the processor is configured to call the operation instruction, and the executable instruction enables the processor to perform an operation corresponding to the dc power flow model optimization method considering the network loss, as shown in the first aspect of the present application.
In an alternative embodiment, an electronic device is provided, as shown in fig. 3, the electronic device 5000 shown in fig. 3 includes: a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are coupled, such as via a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004. It should be noted that the transceiver 5004 is not limited to one in practical application, and the structure of the electronic device 5000 is not limited to the embodiment of the present application.
The processor 5001 may be a CPU, general purpose processor, DSP, ASIC, FPGA or other programmable logic device, transistor logic device, hardware component, or any combination thereof. Which may implement or perform the various illustrative logical blocks, modules, and circuits described in connection with the disclosure. The processor 5001 may also be a combination of processors implementing computing functionality, e.g., comprising one or more microprocessors, a combination of DSPs and microprocessors, and the like.
Bus 5002 can include a path that conveys information between the aforementioned components. The bus 5002 may be a PCI bus or EISA bus, etc. The bus 5002 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in FIG. 3, but this does not mean only one bus or one type of bus.
Memory 5003 may be, but is not limited to, ROM or other type of static storage device that can store static information and instructions, RAM or other type of dynamic storage device that can store information and instructions, EEPROM, CD-ROM or other optical disk storage, optical disk storage (including compact disk, laser disk, optical disk, digital versatile disk, blu-ray disk, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.
The memory 5003 is used for storing application program codes for executing the present solution, and the execution is controlled by the processor 5001. The processor 5001 is configured to execute application program code stored in the memory 5003 to implement the teachings of any of the foregoing method embodiments.
Among them, electronic devices include but are not limited to: a mobile terminal such as a mobile phone, a notebook computer, a digital broadcast receiver, a PDA (personal digital assistant), a PAD (tablet computer), a PMP (portable multimedia player), a car terminal (e.g., a car navigation terminal), etc., and a fixed terminal such as a digital TV, a desktop computer, etc.
A fourth aspect.
The present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements a method for optimizing a dc power flow model considering grid loss according to the first aspect of the present application.
A further embodiment of the present application provides a computer-readable storage medium having stored thereon a computer program which, when run on a computer, causes the computer to perform the respective content of the aforementioned method embodiments.

Claims (10)

1. A direct current power flow model optimization method considering network loss is characterized by comprising the following steps:
on the basis of an alternating current power flow calculation model, when the change values of phase angles and voltages are determined to be smaller than preset values, similarity processing is carried out on the calculation of the phase angles and the voltages in the alternating current power flow calculation model, and the high-order side calculation of the phase angles and the voltages is carried out to reduce the side, so that a simplified alternating current power flow model is obtained; wherein the similarity process is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change the high-order calculation into low-order calculation through Taylor expansion;
and on the basis of the simplified alternating current power flow model, replacing the voltage angle variable with the system initial value to obtain a direct current power flow model considering the network loss.
2. The method as claimed in claim 1, wherein before replacing the voltage and phase angle variables with the system initial values, the method further comprises:
and determining a loss factor according to the function quantity of the voltage in the simplified alternating current power flow model related to the initial value of the phase angle.
3. The method as claimed in claim 2, wherein when it is determined that the variation values of the phase angle and the voltage are smaller than the preset values based on the ac power flow calculation model, performing similarity processing on the calculations of the phase angle and the voltage in the ac power flow calculation model and performing square reduction processing on the high-order-side calculations of the phase angle and the voltage to obtain the simplified ac power flow model, includes:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure FDA0003116458260000011
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
sinθij≈θij，
Figure FDA0003116458260000021
vivjθij≈θij；
Figure FDA0003116458260000022
wherein v isi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure FDA0003116458260000023
Figure FDA0003116458260000024
wherein, thetaij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
4. The grid loss-considered direct current power flow model optimization method according to claim 2, wherein the simplified alternating current power flow model is as follows:
Figure FDA0003116458260000025
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the phase angles of the voltages at the initial states of node i and node j, vi，0，vj，0Representing the initial state voltage magnitudes of node i and node j, respectively.
5. The method as claimed in claim 2, wherein the dc power flow model optimization method considering grid loss is based on the simplified ac power flow model, and the system initial value is used to replace the voltage and phase angle variables, and the calculation is performed by the following formula:
Figure FDA0003116458260000031
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; v. ofi，0，vj，0Representing the initial state voltage magnitudes of node i and node j, respectively.
6. The method for optimizing the direct current power flow model by considering the network loss as claimed in claim 2, wherein the loss factor is calculated by the following formula:
Figure FDA0003116458260000032
wherein, CθIs a constant number of angles, CviAnd CvjIs the constant number of voltages, θ, at node i and node j, respectivelyij，0Is the difference between the voltage phase angles at the initial states of node i and node j.
7. The method for optimizing the direct current power flow model considering the network loss as claimed in claim 6, wherein the direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting node i and nodeThe phase angle difference between j, b represents the susceptance on the line and L represents the loss factor.
8. A direct current power flow model optimization system considering network loss is characterized by comprising:
the numerical value processing module is used for carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model and carrying out square reduction processing on the high-order calculation of the phase angle and the voltage when the change values of the phase angle and the voltage are determined to be smaller than a preset value on the basis of the alternating current power flow calculation model to obtain a simplified alternating current power flow model; wherein the similarity process is to simplify the calculation regarding the phase angle and the voltage; the square reduction processing is to change the high-order calculation into low-order calculation through Taylor expansion;
and the network loss reference module is used for replacing voltage and phase angle variables by system initial values on the basis of simplifying the alternating current power flow model to obtain a direct current power flow model considering network loss.
9. The grid loss-considered direct current power flow model optimization system according to claim 8, further comprising:
and the loss factor determining module is used for determining the loss factor according to the function quantity of the voltage in the simplified alternating current power flow model related to the initial value of the phase angle.
10. The grid loss-based DC power flow model optimization system of claim 9,
on the basis of the alternating current power flow calculation model, when the change values of the phase angle and the voltage are determined to be smaller than the preset values, similarity processing is carried out on the calculation of the phase angle and the voltage in the alternating current power flow calculation model, and square reduction processing is carried out on the calculation of the high order of the phase angle and the voltage, so that the simplified alternating current power flow model is obtained, and the method comprises the following steps:
obtaining the alternating current power flow calculation model; the alternating current power flow calculation model comprises the following steps:
Figure FDA0003116458260000041
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRespectively representing the voltage amplitudes of the node i and the node j;
carrying out similarity processing on the calculation of the phase angle and the voltage in the alternating current power flow calculation model; specifically, the calculation is performed by the following formula:
sinθij≈θij，
Figure FDA0003116458260000051
vivjθij≈θij；
Figure FDA0003116458260000052
wherein v isi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
carrying out square reduction processing on the high-order square calculation of the phase angle and the voltage; specifically, the calculation is performed by the following formula:
Figure FDA0003116458260000053
Figure FDA0003116458260000054
wherein, thetaij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained;
the simplified alternating current power flow model comprises the following steps:
Figure FDA0003116458260000055
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, gijRepresenting the value of the conductance on the line between node i and node j, bijRepresenting susceptance, v, on the line between node i and node ji，vjRepresenting the voltage amplitudes, θ, of node i and node j, respectivelyij，0Is the difference between the phase angles of the voltages at the initial states of node i and node j, vi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
on the basis of the simplified alternating current power flow model, the initial value of the system is used for replacing voltage and phase angle variables, and the calculation is carried out through the following formula:
Figure FDA0003116458260000061
wherein, PijRepresenting the active power on the line between node i and node j, θijRepresenting the phase angle difference between node i and node j, bijRepresenting susceptance, θ, on the line between node i and node jij，0The difference between the voltage phase angles of the initial states of the node i and the node j is obtained; v. ofi，0，vj，0Respectively representing the initial state voltage amplitude of the node i and the node j;
the loss factor is calculated by the following formula:
Figure FDA0003116458260000062
wherein, CθIs a constant number of angles, CviAnd CvjIs the constant number of voltages, θ, at node i and node j, respectivelyij，0Is a section ofThe difference between the voltage phase angles at the initial states of the point i and the node j;
the direct current power flow model considering the network loss is calculated by the following formula:
P＝-bθij+L；
where P represents the active power on the line, θijRepresenting the phase angle difference between node i and node j, b representing the susceptance on the line, and L representing the loss factor.
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