CN115995818A - Power flow calculation method for multi-energy complementary alternating current-direct current hybrid power distribution network - Google Patents

Power flow calculation method for multi-energy complementary alternating current-direct current hybrid power distribution network Download PDF

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CN115995818A
CN115995818A CN202310284536.XA CN202310284536A CN115995818A CN 115995818 A CN115995818 A CN 115995818A CN 202310284536 A CN202310284536 A CN 202310284536A CN 115995818 A CN115995818 A CN 115995818A
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direct current
power
distribution network
module
alternating current
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陈然
周蠡
许汉平
蔡杰
贺兰菲
周英博
李吕满
张赵阳
廖晓红
熊一
孙利平
熊川羽
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Economic and Technological Research Institute of State Grid Hubei Electric Power Co Ltd
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Economic and Technological Research Institute of State Grid Hubei Electric Power Co Ltd
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Abstract

A power flow calculation method of a multi-energy complementary alternating current-direct current hybrid power distribution network comprises the following steps: s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix; s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module; s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module; s4, carrying out alternating iterative convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module to finish calculation; in the application, the power distribution network is divided in a modularized mode, so that the number of network matrixes of each part is reduced, alternating iterative computation is carried out on the alternating current sub-network module and the direct current sub-network module, and the computation iteration speed and flexibility are improved. Therefore, the invention has higher calculation efficiency and more accurate result.

Description

Power flow calculation method for multi-energy complementary alternating current-direct current hybrid power distribution network
Technical Field
The invention relates to a power flow calculation method, belongs to the technical field of active power distribution networks, and particularly relates to a power flow calculation method of a multifunctional complementary alternating current-direct current hybrid power distribution network.
Background
With the continuous development of power electronics technology, an ac-dc hybrid distribution network will be further developed. On one hand, the power flow and the operation control method of the AC/DC system are changed essentially due to the continuous increase of the proportion of the distributed power supply; on the other hand, the continuous increase of the power load can also bring adverse effects to the voltage stability of the direct-current power transmission receiving-end power grid. When the power system is connected with a part of direct current transmission units, the power flow calculation is still performed alternately by taking the alternating current as the main and the direct current as the auxiliary, and when the proportion of the direct current transmission units is continuously increased, the power flow calculation of the alternating current-direct current hybrid power distribution network is required to be performed simultaneously so as to obtain good convergence characteristics. The traditional AC/DC separated power flow calculation convergence effect is poor; the unified calculation method for completely eliminating the direct current variable is adopted, and the sensitivity information related to alternating current and direct current is masked, so that the jacobian matrix structure is complex; when an iteration initial value is selected, the unified power flow calculation method with blindness for reserving the control angle of direct-current transmission prescribes reactive power at the direct-current side, the calculation efficiency is low, the purpose of power flow calculation is also deviated to a certain extent, and a certain deviation exists in the obtained result.
The disclosure of this background section is only intended to increase the understanding of the general background of the application and should not be taken as an admission or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.
Disclosure of Invention
The invention aims to overcome the defects and problems of lower calculation efficiency and certain deviation of results in the prior art, and provides a power flow calculation method for a multi-energy complementary alternating current-direct current hybrid power distribution network, which is lower in calculation efficiency and more accurate in results.
In order to achieve the above object, the technical solution of the present invention is: a power flow calculation method of a multi-energy complementary alternating current-direct current hybrid power distribution network comprises the following steps:
s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix;
s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module;
s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module;
s4, carrying out alternating iteration convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module, outputting a calculation result, and completing calculation.
In the step S1, the step of establishing a loop-branch matrix includes:
s11, acquiring power data information of nodes, loops and branches in a power distribution network topological structure;
s12, numbering nodes and branches in the power distribution network topological structure to obtain a numbered power distribution network topological structure;
s13, based on a topological structure of the numbered distribution network, establishing a standard vector group with the same number as that of loops, determining the number of branches associated with each loop, and acquiring power data of each branch;
and S14, assigning values to the standard vectors corresponding to each loop based on the power data of each branch, so as to obtain feature vector groups of different loops, and constructing a loop-branch matrix according to the different feature vector groups.
In the step S2, the dividing of the power flow calculation module means: and taking the converter as a boundary, carrying out modularized division on the power distribution network, and dividing the power distribution network into an alternating current sub-network module, a direct current sub-network module and a converter module.
In the step S3, the step of setting the initial values, the positive directions and the convergence accuracy of the ac subnet module and the dc subnet module includes:
s31, collecting node types of a power distribution network topological structure, and classifying the node types according to the attribute of the nodes;
and S32, assigning values to the node attributes of different classifications according to parameters of the alternating current sub-network module and the direct current sub-network module to obtain initial values, and setting positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module.
In the step S4, the step of performing alternating iterative convergence judgment of the alternating current sub-network module and the direct current sub-network module includes:
s41, calculating an unbalance amount according to the established loop-branch matrix and combining the initial value and the positive direction
Figure SMS_1
、
Figure SMS_2
And->
Figure SMS_3
The method comprises the steps of carrying out a first treatment on the surface of the Wherein: />
Figure SMS_4
、/>
Figure SMS_5
The active unbalance amount and the reactive unbalance amount of the system node are respectively; />
Figure SMS_6
The active unbalance amount of the system node under different control modes is calculated;
s42, judging the unbalance amount according to the convergence accuracy
Figure SMS_7
、/>
Figure SMS_8
And->
Figure SMS_9
Whether to converge;
if the power flow of each branch and the running parameters of the direct current transmission unit are converged, calculating the running parameters of each branch and the running parameters of the direct current transmission unit until the power flow calculation of the alternating current sub-network module and the power flow calculation of the direct current sub-network module are converged, outputting a calculation result, and finishing the power flow calculation;
if not, preprocessing the direct current output unit, establishing a jacobian matrix of the alternating current transmission system, adding a micro-addition model and a newly added constraint equation of the direct current transmission unit according to a control mode, solving and correcting the micro-addition model and the newly added constraint equation, correcting voltage and direct current of each node, and repeating the step S42.
In the step S42, the step of calculating the power flow of each branch is as follows:
s421, carrying out alternating current sub-network module power flow calculation until calculation convergence;
s422, carrying out current calculation of a current converter module to obtain current converter current and loss, carrying out-of-limit check on whether the current converter is out of limit according to the current converter current and the loss, and if so, carrying out step S422; if not, go to step S423;
s423, carrying out direct current sub-network module power flow calculation; if the calculation is converged, judging that the power flow calculation is finished, and outputting a result to finish the power flow calculation; if the calculation is not converged, step S421 is performed until the calculation is converged.
In the step S42, the preprocessing refers to: the node power balance equation expression is unified using the following formula:
Figure SMS_10
；
Figure SMS_11
；
wherein:
Figure SMS_21
for injecting nodes->
Figure SMS_15
Ac active power of (a); />
Figure SMS_18
For injecting nodes->
Figure SMS_24
Ac reactive power of (a); />
Figure SMS_29
For injecting nodes->
Figure SMS_28
Direct current active power of (2); />
Figure SMS_31
For injecting nodes->
Figure SMS_22
Direct current reactive power of (2); />
Figure SMS_25
For node->
Figure SMS_12
Is a voltage of (2); />
Figure SMS_19
For node->
Figure SMS_14
Is a voltage of (2); />
Figure SMS_17
、/>
Figure SMS_20
Nodes +.>
Figure SMS_23
、/>
Figure SMS_16
Connected conductance and susceptance; />
Figure SMS_26
For node->
Figure SMS_27
、/>
Figure SMS_30
Is a voltage cross-over of (2);
Figure SMS_13
is the inherent loss of the converter;
the flow equation expression of the direct current sub-network module is as follows:
Figure SMS_32
；
wherein:
Figure SMS_33
active power injected into the direct current side of the converter; />
Figure SMS_34
Active power injected for the ac side; />
Figure SMS_35
Is the current flowing through the inverter; />
Figure SMS_36
Is the equivalent resistance of the converter.
In the step S42, equations of the micro-increment model and the constraint equation are as follows:
Figure SMS_37
；
wherein:
Figure SMS_40
、/>
Figure SMS_44
、/>
Figure SMS_46
the unbalance amount of the direct current active power, the alternating current active power and the reactive power are respectively; />
Figure SMS_39
Is the phase angle of the alternating voltage; />
Figure SMS_45
Is direct current active power; />
Figure SMS_47
Is a direct current; />
Figure SMS_50
Is the voltage of an alternating current node; />
Figure SMS_38
、/>
Figure SMS_42
、/>
Figure SMS_48
、/>
Figure SMS_49
Alternating current elements in the Jacobian matrix; />
Figure SMS_41
、/>
Figure SMS_43
Is a direct current element in the jacobian matrix.
In the step S3, the control manner includes the following steps: first kind: rectifying side constant current and inverting side constant voltage; second kind: rectifying side constant current and inverting side constant arc extinguishing angle; third kind: a rectification side is fixed with power and an inversion side is fixed with voltage; fourth kind: the rectification side is fixed with power, and the inversion side is fixed with arc extinguishing angle; fifth: the triggering angle is fixed at the rectifying side, and the current is fixed at the inverting side.
In step S12, numbering nodes and branches in the topology structure of the power distribution network means:
firstly, setting an access point of a power distribution network and an upper power grid as a first node, setting the number of the access point as 0, setting the number of a branch related to the first node as 1, increasing the numbers of branches diverged by the branches with the number of 1 along the forward direction, enabling the numbers of other nodes except the first node to be consistent with the numbers of branches pointing to the nodes, enabling the numbers of the branches connected to the ground through the nodes to be consistent with the numbers of the nodes correspondingly connected with the ground, and numbering the branches to obtain a topological structure of the numbered power distribution network.
Compared with the prior art, the invention has the beneficial effects that:
according to the power flow calculation method for the multi-energy complementary alternating current-direct current hybrid power distribution network, the power distribution network is modularized, so that the number of network matrixes of each part is reduced, alternating current sub-network modules and direct current sub-network modules are subjected to alternating iterative calculation convergence judgment, the power flow calculation difficulty of the alternating current-direct current hybrid power distribution network is reduced, the calculation speed, the flexibility and the algorithm convergence speed are improved, the accuracy of a result is improved to a certain extent, and meanwhile, the method can be applied to other power distribution network calculation and has certain universality. Therefore, the method and the device have higher calculation efficiency and more accurate results.
Drawings
Fig. 1 is a schematic flow chart of the present invention.
Fig. 2 is a node power flow model diagram of the ac/dc hybrid power distribution network of the present invention.
Fig. 3 is a flow chart of the load flow calculation of the present invention.
Fig. 4 is a topological structure diagram of the multi-energy complementary ac/dc hybrid distribution network of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings and detailed description.
Referring to fig. 1-4, a power flow calculation method of a multi-energy complementary ac/dc hybrid power distribution network includes the following steps:
s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix;
s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module;
s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module;
s4, carrying out alternating iteration convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module, outputting a calculation result, and completing calculation.
In the step S1, the step of establishing a loop-branch matrix includes:
s11, acquiring power data information of nodes, loops and branches in a power distribution network topological structure;
s12, numbering nodes and branches in the power distribution network topological structure to obtain a numbered power distribution network topological structure;
s13, based on a topological structure of the numbered distribution network, establishing a standard vector group with the same number as that of loops, determining the number of branches associated with each loop, and acquiring power data of each branch;
and S14, assigning values to the standard vectors corresponding to each loop based on the power data of each branch, so as to obtain feature vector groups of different loops, and constructing a loop-branch matrix according to the different feature vector groups.
In the step S2, the dividing of the power flow calculation module means: and taking the converter as a boundary, carrying out modularized division on the power distribution network, and dividing the power distribution network into an alternating current sub-network module, a direct current sub-network module and a converter module.
In the step S3, the step of setting the initial values, the positive directions and the convergence accuracy of the ac subnet module and the dc subnet module includes:
s31, collecting node types of a power distribution network topological structure, and classifying the node types according to the attribute of the nodes;
and S32, assigning values to the node attributes of different classifications according to parameters of the alternating current sub-network module and the direct current sub-network module to obtain initial values, and setting positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module.
In the step S4, the step of performing alternating iterative convergence judgment of the alternating current sub-network module and the direct current sub-network module includes:
s41, calculating an unbalance amount according to the established loop-branch matrix and combining the initial value and the positive direction
Figure SMS_51
、
Figure SMS_52
And->
Figure SMS_53
The method comprises the steps of carrying out a first treatment on the surface of the Wherein: />
Figure SMS_54
、/>
Figure SMS_55
The active unbalance amount and the reactive unbalance amount of the system node are respectively; />
Figure SMS_56
The active unbalance amount of the system node under different control modes is calculated;
s42, judging the unbalance amount according to the convergence accuracy
Figure SMS_57
、/>
Figure SMS_58
And->
Figure SMS_59
Whether to converge;
if the power flow of each branch and the running parameters of the direct current transmission unit are converged, calculating the running parameters of each branch and the running parameters of the direct current transmission unit until the power flow calculation of the alternating current sub-network module and the power flow calculation of the direct current sub-network module are converged, outputting a calculation result, and finishing the power flow calculation;
if not, preprocessing the direct current output unit, establishing a jacobian matrix of the alternating current transmission system, adding a micro-addition model and a newly added constraint equation of the direct current transmission unit according to a control mode, solving and correcting the micro-addition model and the newly added constraint equation, correcting voltage and direct current of each node, and repeating the step S42.
In the step S42, the step of calculating the power flow of each branch is as follows:
s421, carrying out alternating current sub-network module power flow calculation until calculation convergence;
s422, carrying out current calculation of a current converter module to obtain current converter current and loss, carrying out-of-limit check on whether the current converter is out of limit according to the current converter current and the loss, and if so, carrying out step S422; if not, go to step S423;
s423, carrying out direct current sub-network module power flow calculation; if the calculation is converged, judging that the power flow calculation is finished, and outputting a result to finish the power flow calculation; if the calculation is not converged, step S421 is performed until the calculation is converged.
In the step S42, the preprocessing refers to: the node power balance equation expression is unified using the following formula:
Figure SMS_60
；
Figure SMS_61
；
wherein:
Figure SMS_72
for injecting nodes->
Figure SMS_65
Ac active power of (a); />
Figure SMS_68
For injecting nodes->
Figure SMS_76
Ac reactive power of (a); />
Figure SMS_81
For injecting nodes->
Figure SMS_78
Direct current active power of (2); />
Figure SMS_80
For injecting nodes->
Figure SMS_70
Direct current reactive power of (2); />
Figure SMS_75
For node->
Figure SMS_62
Is a voltage of (2); />
Figure SMS_66
For node->
Figure SMS_63
Is a voltage of (2); />
Figure SMS_67
、/>
Figure SMS_71
Nodes +.>
Figure SMS_74
、/>
Figure SMS_69
Connected conductance and susceptance; />
Figure SMS_73
For node->
Figure SMS_77
、/>
Figure SMS_79
Is a voltage cross-over of (2);
Figure SMS_64
is the inherent loss of the converter;
the flow equation expression of the direct current sub-network module is as follows:
Figure SMS_82
；
wherein:
Figure SMS_83
active power injected into the direct current side of the converter; />
Figure SMS_84
Active power injected for the ac side; />
Figure SMS_85
Is the current flowing through the inverter; />
Figure SMS_86
Is the equivalent resistance of the converter.
In the step S42, equations of the micro-increment model and the constraint equation are as follows:
Figure SMS_87
；
wherein:
Figure SMS_90
、/>
Figure SMS_94
、/>
Figure SMS_97
the unbalance amount of the direct current active power, the alternating current active power and the reactive power are respectively; />
Figure SMS_91
Is the phase angle of the alternating voltage; />
Figure SMS_93
Is direct current active power; />
Figure SMS_98
Is a direct current; />
Figure SMS_100
Is the voltage of an alternating current node; />
Figure SMS_88
、/>
Figure SMS_92
、/>
Figure SMS_96
、/>
Figure SMS_99
Alternating current elements in the Jacobian matrix; />
Figure SMS_89
、/>
Figure SMS_95
Is a direct current element in the jacobian matrix.
In the step S3, the control manner includes the following steps: first kind: rectifying side constant current and inverting side constant voltage; second kind: rectifying side constant current and inverting side constant arc extinguishing angle; third kind: a rectification side is fixed with power and an inversion side is fixed with voltage; fourth kind: the rectification side is fixed with power, and the inversion side is fixed with arc extinguishing angle; fifth: the triggering angle is fixed at the rectifying side, and the current is fixed at the inverting side.
In step S12, numbering nodes and branches in the topology structure of the power distribution network means:
firstly, setting an access point of a power distribution network and an upper power grid as a first node, setting the number of the access point as 0, setting the number of a branch related to the first node as 1, increasing the numbers of branches diverged by the branches with the number of 1 along the forward direction, enabling the numbers of other nodes except the first node to be consistent with the numbers of branches pointing to the nodes, enabling the numbers of the branches connected to the ground through the nodes to be consistent with the numbers of the nodes correspondingly connected with the ground, and numbering the branches to obtain a topological structure of the numbered power distribution network.
Example 1:
referring to fig. 1-4, a power flow calculation method of a multi-energy complementary ac/dc hybrid power distribution network includes the following steps:
s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix;
further, constructing a topology structure of the power distribution network refers to: converting an actual preset circuit into a graph mode, describing the structure of the circuit in modes of nodes, loops and the like, and obtaining the topological structure of the power distribution network by determining the number of the needed nodes, the number of the loops, the number of branches and the reference direction;
further, the step of establishing a loop-leg matrix includes the steps of:
s11, acquiring power data information of nodes, loops and branches in a power distribution network topological structure;
s12, numbering nodes and branches in the power distribution network topological structure to obtain a numbered power distribution network topological structure;
preferably, in the step S12, numbering the nodes and branches in the topology structure of the power distribution network means:
firstly, setting an access point of a power distribution network and an upper power grid as a first node, setting the number of the access point as 0, setting the number of a branch related to the first node as 1, increasing the numbers of branches diverged by the branches with the number of 1 along the forward direction, enabling the numbers of other nodes except the first node to be consistent with the numbers of branches pointing to the nodes, enabling the numbers of the branches connected to the ground through the nodes to be consistent with the numbers of the nodes correspondingly connected with the ground, and numbering the branches to obtain a topological structure of the numbered power distribution network; the power distribution network is generally in a tree network structure, taking the case that N nodes exist in the power distribution network as an example, the power distribution network with N nodes is provided with N-1=n independent loops, and each node and branch of the power distribution network with N nodes are numbered according to the above, so that a numbered power distribution network topological structure can be obtained;
s13, based on a topological structure of the numbered distribution network, establishing a standard vector group with the same number as that of loops, determining the number of branches associated with each loop, and acquiring power data of each branch; the power data comprises reactance, resistance, impedance and the like of each branch;
s14, assigning values to the standard vectors corresponding to each loop based on the power data of each branch, so as to obtain feature vector groups of different loops, and constructing a loop-branch matrix according to the different feature vector groups;
s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module;
further, the dividing of the power flow calculation module refers to: taking the converter as a boundary, carrying out modularized division on the power distribution network, and dividing the power distribution network into an alternating current sub-network module, a direct current sub-network module and a converter module;
s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module;
further, the control method comprises the following steps: first kind: rectifying side constant current and inverting side constant voltage; second kind: rectifying side constant current and inverting side constant arc extinguishing angle; third kind: a rectification side is fixed with power and an inversion side is fixed with voltage; fourth kind: the rectification side is fixed with power, and the inversion side is fixed with arc extinguishing angle; fifth: the rectification side sets a triggering angle and the inversion side sets a current; during calculation, any one or any combination of the two is selected according to actual conditions;
further, the step of setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module includes:
s31, collecting node types of a power distribution network topological structure, and classifying the node types according to the attribute of the nodes;
preferably, the node type comprises a PV node and a PQ node, and the node voltage and the active power of the PV node are constant values; the node active power and reactive power of the PQ node are constant values;
s32, assigning values to node attributes of different classifications according to parameters of the alternating current sub-network module and the direct current sub-network module to obtain initial values, and setting positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module;
s4, carrying out alternating iteration convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module, outputting a calculation result, and completing calculation;
further, the step of performing alternating iterative convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module includes:
s41, calculating an unbalance amount according to the established loop-branch matrix and combining the initial value and the positive direction
Figure SMS_101
、
Figure SMS_102
And->
Figure SMS_103
The method comprises the steps of carrying out a first treatment on the surface of the Wherein: />
Figure SMS_104
、/>
Figure SMS_105
The active unbalance amount and the reactive unbalance amount of the system node are respectively; />
Figure SMS_106
The active unbalance amount of the system node under different control modes is calculated;
s42, judging the unbalance amount according to the convergence accuracy
Figure SMS_107
、/>
Figure SMS_108
And->
Figure SMS_109
Whether to converge;
if the power flow of each branch and the running parameters of the direct current transmission unit are converged, calculating the running parameters of each branch and the running parameters of the direct current transmission unit until the power flow calculation of the alternating current sub-network module and the power flow calculation of the direct current sub-network module are converged, outputting a calculation result, and finishing the power flow calculation;
if not, preprocessing the direct current output unit, establishing a jacobian matrix of the alternating current transmission system, adding a micro-addition model and a newly added constraint equation of the direct current transmission unit according to a control mode, solving and correcting the micro-addition model and the newly added constraint equation, correcting voltage and direct current of each node, and repeating the step S42;
further, in step S42, the step of calculating the power flow of each branch is as follows:
s421, carrying out alternating current sub-network module power flow calculation until calculation convergence;
preferably, the converter module is regarded as a load when the alternating current sub-network module calculates, the absorbed power is positive, and the direct current sub-network module and the converter module are assumed to have no power loss, and the initial value of the converter module is brought into the alternating current sub-network module to carry out load flow calculation;
s422, carrying out current calculation of a current converter module to obtain current converter current and loss, carrying out-of-limit check on whether the current converter is out of limit according to the current converter current and the loss, and if so, carrying out step S422; if not, go to step S423;
preferably, the load flow calculation of the converter module is performed by using a VSC model, the power input into the converter module by the AC sub-network module is taken as an initial value, out-of-limit detection is performed on the direct-current side power and the voltage of the converter module after the direct-current side power and the voltage of the converter module are calculated, and the operation constraint of the out-of-limit detection of the VSC is expressed as the following formula:
Figure SMS_110
；
Figure SMS_111
；
wherein:
Figure SMS_112
、/>
Figure SMS_113
the lower limit and the upper limit of the VSC operation voltage are respectively; />
Figure SMS_114
、/>
Figure SMS_115
The upper limit and the lower limit of active output and reactive output of the VSC are respectively;
s423, carrying out direct current sub-network module power flow calculation; if the calculation is converged, judging that the power flow calculation is finished, and outputting a result to finish the power flow calculation; if the convergence is impossible, step S421 is performed until the calculation is converged;
preferably, the output power obtained by the current converter module power flow calculation is used as the input of the direct current sub-network module power flow calculation, and the input power is negative;
preferably, in step S42, the preprocessing preferably uses the following formula, so that the node power balance equation expression is unified, where the formula is as follows:
Figure SMS_116
；
Figure SMS_117
；
wherein:
Figure SMS_128
for injecting nodes->
Figure SMS_120
Ac active power of (a); />
Figure SMS_123
For injecting nodes->
Figure SMS_132
Ac reactive power of (a); />
Figure SMS_137
For injecting nodes->
Figure SMS_133
Direct current active power of (2); />
Figure SMS_136
For injecting nodes->
Figure SMS_126
Direct current reactive power of (2); />
Figure SMS_130
For node->
Figure SMS_118
Is a voltage of (2); />
Figure SMS_122
For node->
Figure SMS_119
Is a voltage of (2); />
Figure SMS_125
、/>
Figure SMS_131
Nodes +.>
Figure SMS_134
、/>
Figure SMS_124
Connected conductance and susceptance; />
Figure SMS_127
For node->
Figure SMS_129
、/>
Figure SMS_135
Is a voltage cross-over of (2);
Figure SMS_121
is the inherent loss of the converter;
the flow equation expression of the direct current sub-network module is as follows:
Figure SMS_138
；
wherein:
Figure SMS_139
active power injected into the direct current side of the converter; />
Figure SMS_140
Active power injected for the ac side; />
Figure SMS_141
Is the current flowing through the inverter; />
Figure SMS_142
Is the equivalent resistance of the converter;
preferably, the micro-increment model in step S42 and the constraint equation are preferably as follows:
Figure SMS_143
；
wherein:
Figure SMS_145
、/>
Figure SMS_148
、/>
Figure SMS_152
the unbalance amount of the direct current active power, the alternating current active power and the reactive power are respectively; />
Figure SMS_147
Is the phase angle of the alternating voltage; />
Figure SMS_151
Is direct current active power; />
Figure SMS_153
Is a direct current; />
Figure SMS_155
Is the voltage of an alternating current node; />
Figure SMS_144
、/>
Figure SMS_149
、/>
Figure SMS_154
、/>
Figure SMS_156
Alternating current elements in the Jacobian matrix; />
Figure SMS_146
、/>
Figure SMS_150
Is a direct current element in the jacobian matrix.
The above description is merely of preferred embodiments of the present invention, and the scope of the present invention is not limited to the above embodiments, but all equivalent modifications or variations according to the present disclosure will be within the scope of the claims.

Claims (10)

1. The utility model provides a method for calculating the tide of a multifunctional complementary alternating current-direct current hybrid power distribution network, which is characterized by comprising the following steps:
s1, acquiring power lines of related equipment nodes, constructing a topological structure of a power distribution network, acquiring topological structure information, and establishing a loop-branch matrix;
s2, dividing a power flow calculation module based on a topological structure of the power distribution network, and dividing the power flow calculation module into an alternating current sub-network module, a direct current sub-network module and a converter module;
s3, setting a control mode of the direct current sub-network module, and setting initial values, positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module;
s4, carrying out alternating iteration convergence judgment on the power flow calculation of the alternating current sub-network module and the direct current sub-network module, outputting a calculation result, and completing calculation.
2. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 1, which is characterized by comprising the following steps of:
in the step S1, the step of establishing a loop-branch matrix includes:
s11, acquiring power data information of nodes, loops and branches in a power distribution network topological structure;
s12, numbering nodes and branches in the power distribution network topological structure to obtain a numbered power distribution network topological structure;
s13, based on a topological structure of the numbered distribution network, establishing a standard vector group with the same number as that of loops, determining the number of branches associated with each loop, and acquiring power data of each branch;
and S14, assigning values to the standard vectors corresponding to each loop based on the power data of each branch, so as to obtain feature vector groups of different loops, and constructing a loop-branch matrix according to the different feature vector groups.
3. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 1, which is characterized by comprising the following steps of:
in the step S2, the dividing of the power flow calculation module means: and taking the converter as a boundary, carrying out modularized division on the power distribution network, and dividing the power distribution network into an alternating current sub-network module, a direct current sub-network module and a converter module.
4. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 1, which is characterized by comprising the following steps of:
in the step S3, the step of setting the initial values, the positive directions and the convergence accuracy of the ac subnet module and the dc subnet module includes:
s31, collecting node types of a power distribution network topological structure, and classifying the node types according to the attribute of the nodes;
and S32, assigning values to the node attributes of different classifications according to parameters of the alternating current sub-network module and the direct current sub-network module to obtain initial values, and setting positive directions and convergence accuracy of the alternating current sub-network module and the direct current sub-network module.
5. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 1, which is characterized by comprising the following steps of:
in the step S4, the step of performing alternating iterative convergence judgment of the alternating current sub-network module and the direct current sub-network module includes:
s41, calculating an unbalance amount according to the established loop-branch matrix and combining the initial value and the positive direction
Figure QLYQS_1
、/>
Figure QLYQS_2
And->
Figure QLYQS_3
The method comprises the steps of carrying out a first treatment on the surface of the Wherein: />
Figure QLYQS_4
、/>
Figure QLYQS_5
The active unbalance amount and the reactive unbalance amount of the system node are respectively; />
Figure QLYQS_6
The active unbalance amount of the system node under different control modes is calculated;
s42, judging the unbalance amount according to the convergence accuracy
Figure QLYQS_7
、/>
Figure QLYQS_8
And->
Figure QLYQS_9
Whether to converge;
if the power flow of each branch and the running parameters of the direct current transmission unit are converged, calculating the running parameters of each branch and the running parameters of the direct current transmission unit until the power flow calculation of the alternating current sub-network module and the power flow calculation of the direct current sub-network module are converged, outputting a calculation result, and finishing the power flow calculation;
if not, preprocessing the direct current output unit, establishing a jacobian matrix of the alternating current transmission system, adding a micro-addition model and a newly added constraint equation of the direct current transmission unit according to a control mode, solving and correcting the micro-addition model and the newly added constraint equation, correcting voltage and direct current of each node, and repeating the step S42.
6. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 5, which is characterized by comprising the following steps:
in the step S42, the step of calculating the power flow of each branch is as follows:
s421, carrying out alternating current sub-network module power flow calculation until calculation convergence;
s422, carrying out current calculation of a current converter module to obtain current converter current and loss, carrying out-of-limit check on whether the current converter is out of limit according to the current converter current and the loss, and if so, carrying out step S422; if not, go to step S423;
s423, carrying out direct current sub-network module power flow calculation; if the calculation is converged, judging that the power flow calculation is finished, and outputting a result to finish the power flow calculation; if the calculation is not converged, step S421 is performed until the calculation is converged.
7. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 6, wherein the method comprises the following steps:
in the step S42, the preprocessing refers to: the node power balance equation expression is unified using the following formula:
Figure QLYQS_10
；
Figure QLYQS_11
；
wherein:
Figure QLYQS_20
for injecting nodes->
Figure QLYQS_14
Ac active power of (a); />
Figure QLYQS_16
For injecting nodes->
Figure QLYQS_13
Ac reactive power of (a); />
Figure QLYQS_17
For injecting nodes->
Figure QLYQS_21
Direct current active power of (2); />
Figure QLYQS_25
For injecting nodes->
Figure QLYQS_22
Direct current reactive power of (2); />
Figure QLYQS_28
For node->
Figure QLYQS_12
Is a voltage of (2); />
Figure QLYQS_19
For node->
Figure QLYQS_24
Is a voltage of (2); />
Figure QLYQS_27
、/>
Figure QLYQS_29
Nodes +.>
Figure QLYQS_31
、/>
Figure QLYQS_18
Connected conductance and susceptance; />
Figure QLYQS_23
For node->
Figure QLYQS_26
、/>
Figure QLYQS_30
Is a voltage cross-over of (2); />
Figure QLYQS_15
For the purpose of current conversionInherent loss of the device;
the flow equation expression of the direct current sub-network module is as follows:
Figure QLYQS_32
；
wherein:
Figure QLYQS_33
active power injected into the direct current side of the converter; />
Figure QLYQS_34
Active power injected for the ac side; />
Figure QLYQS_35
Is the current flowing through the inverter; />
Figure QLYQS_36
Is the equivalent resistance of the converter.
8. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 7, wherein the method comprises the following steps of:
in the step S42, equations of the micro-increment model and the constraint equation are as follows:
Figure QLYQS_37
；
wherein:
Figure QLYQS_38
、/>
Figure QLYQS_42
、/>
Figure QLYQS_46
the unbalance amount of the direct current active power, the alternating current active power and the reactive power are respectively; />
Figure QLYQS_41
Is the phase angle of the alternating voltage; />
Figure QLYQS_45
Is direct current active power; />
Figure QLYQS_48
Is a direct current; />
Figure QLYQS_50
Is the voltage of an alternating current node; />
Figure QLYQS_39
、/>
Figure QLYQS_44
、/>
Figure QLYQS_47
、
Figure QLYQS_49
Alternating current elements in the Jacobian matrix; />
Figure QLYQS_40
、/>
Figure QLYQS_43
Is a direct current element in the jacobian matrix.
9. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to any one of claims 1 to 6, wherein the method comprises the following steps:
in the step S3, the control manner includes the following steps: first kind: rectifying side constant current and inverting side constant voltage; second kind: rectifying side constant current and inverting side constant arc extinguishing angle; third kind: a rectification side is fixed with power and an inversion side is fixed with voltage; fourth kind: the rectification side is fixed with power, and the inversion side is fixed with arc extinguishing angle; fifth: the triggering angle is fixed at the rectifying side, and the current is fixed at the inverting side.
10. The method for calculating the power flow of the multi-energy complementary alternating current-direct current hybrid power distribution network according to claim 2, which is characterized by comprising the following steps of:
in step S12, numbering nodes and branches in the topology structure of the power distribution network means:
firstly, setting an access point of a power distribution network and an upper power grid as a first node, setting the number of the access point as 0, setting the number of a branch related to the first node as 1, increasing the numbers of branches diverged by the branches with the number of 1 along the forward direction, enabling the numbers of other nodes except the first node to be consistent with the numbers of branches pointing to the nodes, enabling the numbers of the branches connected to the ground through the nodes to be consistent with the numbers of the nodes correspondingly connected with the ground, and numbering the branches to obtain a topological structure of the numbered power distribution network.
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