CN113690892A - Hybrid power distribution network power flow model considering energy router and solving method - Google Patents

Hybrid power distribution network power flow model considering energy router and solving method Download PDF

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Publication number
CN113690892A
CN113690892A CN202110983514.3A CN202110983514A CN113690892A CN 113690892 A CN113690892 A CN 113690892A CN 202110983514 A CN202110983514 A CN 202110983514A CN 113690892 A CN113690892 A CN 113690892A
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port
power
node
distribution network
voltage
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Inventor
张辉
朱刘柱
荣秀婷
赵洁
沈玉明
贾陈伊洋
吴润东
王绪利
麻高源
施天成
周帆
高廷峰
朱灿
唐佳杰
方宇迪
何育钦
李蕊
沙广林
张姚
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Wuhan University WHU
Economic and Technological Research Institute of State Grid Anhui Electric Power Co Ltd
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Wuhan University WHU
Economic and Technological Research Institute of State Grid Anhui Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

Abstract

The invention relates to a hybrid power distribution network power flow model considering an energy router and a solving method, and compared with the prior art, the hybrid power distribution network power flow model considering the energy router is difficult to establish. The invention comprises the following steps: modeling a typical structure of the information of the hybrid power distribution network; establishing a steady-state model of the energy router; establishing a power flow model of a hybrid power distribution network; and solving the power flow model of the hybrid power distribution network. The alternating current-direct current hybrid power distribution network model considering the energy router is established based on analysis of the topological structure of the alternating current-direct current hybrid power distribution network, the alternating iteration method considering the correction step length and the adaptive multiplier optimization with stronger adaptability is provided, the method can be used for the optimization analysis and calculation of the running state of the alternating current-direct current hybrid power distribution network, and has important theoretical significance and practical application engineering value, and the parameters required by calculation are easy to obtain, and the practicability is strong.

Description

Hybrid power distribution network power flow model considering energy router and solving method
Technical Field
The invention relates to the technical field of power distribution network operation analysis of a power system, in particular to a hybrid power distribution network load flow model considering an energy router and a solving method.
Background
In recent years, an alternating current power distribution network becomes a main form in the field of power distribution at present with the advantages of convenience in planning and laying, mature engineering practice, rich operation and maintenance experience and the like, but due to continuous development of new technologies, new equipment and new elements related to the power distribution network, the construction and planning of the power distribution network are influenced, and meanwhile, many challenges such as economy and stability are brought. Conventional power distribution architectures are demanding more flexible, economical, and environmentally friendly power distribution formats to address these problems of low voltage power distribution systems. The current research focuses on an alternating current-direct current hybrid power distribution network, the type and the number of nodes of the alternating current-direct current hybrid power distribution network are large, grid-connected elements are rich, so that the trend and the control among the networks are more complex, the traditional electric energy centralized coordination control needs to be flexibly adjusted, and the current flexible power distribution network based on Energy Router (ER) networking can effectively solve the problems.
Based on a flexible power distribution network structure of an energy router networking, an ER-considered alternating current and direct current hybrid power distribution network load flow calculation model is established, reasonable planning construction of the alternating current and direct current hybrid power distribution network and implementation of equipment distribution work can be guided, and safe, high-quality and economic operation of the hybrid power distribution network is achieved. The traditional hybrid network solving algorithm cannot perfectly unify convergence and calculation speed, and the hybrid power distribution network load flow model considering the energy router is complex, so that it is important to consider both the convergence and the calculation speed.
Disclosure of Invention
The invention aims to solve the defect that a hybrid power distribution network power flow model for an energy router is difficult to establish in the prior art, and provides the hybrid power distribution network power flow model for the energy router and a solving method thereof to solve the problems.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a hybrid power distribution network power flow model considering an energy router and a solving method thereof comprise the following steps:
11) modeling of a typical structure of hybrid distribution network information: reading information of the hybrid power distribution network, and performing steady-state modeling on a typical structure of the hybrid power distribution network based on a Newton-Raphson method;
12) establishing an energy router steady-state model: establishing a multi-port accessed energy router steady-state model based on a hierarchical power electronic structure of the energy router;
13) establishing a power flow model of the hybrid power distribution network: establishing a hybrid power distribution network power flow model considering an energy router;
14) solving a hybrid power distribution network power flow model: and (4) introducing a correction step-adaptive multiplier optimization method, and solving a hybrid power distribution network power flow model based on the energy router parameters and a control mode.
The establishment of the energy router steady-state model comprises the following steps:
21) setting a multi-port accessed energy router steady-state model to comprise an alternating current port steady-state model and a direct current port steady-state model;
22) modeling an alternating current port steady-state model:
based on the power electronic framework of the standardized ER, if the node i is connected to the AC port of the ER, the voltage is Ui∠θiThe point corresponds to an ER newly-added node h with the alternating voltage of Uh∠θhThen δih＝δi-δh；
The reactance between node i and node h is Yih＝Gih+jBihThe port capacitance is BsiThen, the active and reactive powers injected into i are as follows:
Figure BDA0003229792330000021
in the formula:
Figure BDA0003229792330000022
the active power and the reactive power of the node i are obtained; gih，BihIs the conductance and susceptance between nodes; b issiIs a port capacitance; deltaihIs the phase angle difference between the nodes;
active power injected into node h is
Figure BDA0003229792330000023
In the formula:
Figure BDA0003229792330000024
injecting active power of the node h; gih，BihIs the conductance and susceptance between nodes; deltaihIs the phase angle difference between the nodes;
the internal losses are equivalent to the port impedance, and the power of the ER internal collection bus
Figure BDA0003229792330000031
And
Figure BDA0003229792330000032
the same;
khfor the port voltage transformation ratio, ER internal collection bus voltage EerIs composed of
Figure BDA0003229792330000033
In the formula: eerFor collecting the bus voltage, U, inside the ERhVoltage of node h, khIs the port voltage transformation ratio; the loss of the AC port satisfies
Figure BDA0003229792330000034
In the formula:
Figure BDA0003229792330000035
is the active power of the node i and,
Figure BDA0003229792330000036
active power of a collecting bus inside the ER is injected into a port;
23) modeling a direct current port steady state model:
based on the direct current port in the ER, the port model is based on a DC/DC converter;
assume that the DC aggregate bus voltage with its primary side connected to ER is EkThe voltage of the secondary side connected to the DC network is El，
Figure BDA0003229792330000037
And
Figure BDA0003229792330000038
for active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio, satisfying the following:
Figure BDA0003229792330000039
in the formula: ekFor collecting the bus voltage for primary connection to ER, ElThe bus voltage is collected for dc that is primary connected to the ER,
Figure BDA00032297923300000310
and
Figure BDA00032297923300000311
for active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio;
the power loss of the branch port is the power difference between the primary side and the secondary side, and the following formula is adopted:
Figure BDA00032297923300000312
in the formula:
Figure BDA0003229792330000041
and
Figure BDA0003229792330000042
for active power on both sides of the port, EkFor collecting the bus voltage for primary connection to ER, ElFor a DC collective bus voltage primary-connected to ER, RklFor internal losses, n is the voltage transformation ratio;
if the number of the alternating current ports and the direct current ports of the ER are x and y respectively, neglecting static loss, then the operation loss delta Per,lossIs composed of
Figure BDA0003229792330000043
In the formula:
Figure BDA0003229792330000044
the loss at the ac port is reduced,
Figure BDA0003229792330000045
loss of dc port.
The establishment of the hybrid power distribution network power flow model comprises the following steps:
31) according to the established alternating current port steady-state model and the established direct current port steady-state model, an alternating current and direct current hybrid network mathematical model and an ER are combined together in a unified mode to form an alternating current and direct current hybrid power distribution network power flow model considering the energy router;
32) carrying out load flow calculation on nodes connected with ER by using the actual value of the mixed distribution network information;
33) if the port number of the ER is regarded as a network virtual node, the network is divided into an alternating current network part and a direct current network part, wherein the alternating current network comprises an alternating current node of an original branch and an alternating current port equivalent node provided by the ER, and the direct current network comprises a direct current node of the original branch and a direct current port equivalent node provided by the ER;
at this time, the system power flow equation is as follows:
Figure BDA0003229792330000046
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000047
is an equation for the power of the node,
Figure BDA0003229792330000048
for ER control equation, the system waits for the electrical quantity xsIs a voltage (U)i,Uh,Eiso,El) And phase angle (theta)i,θh)；
34) Considering the plug-and-play function of the ER for the distributed energy, the ER port is equivalent to an active input port, and the injected alternating current power equation is as follows:
Figure BDA0003229792330000051
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000052
power is injected for the VSC port of the ER and active power at the node respectively,
Figure BDA0003229792330000053
Figure BDA0003229792330000054
is the reactive power corresponding to the power value of the power,
Figure BDA0003229792330000055
for admittance between nodes, deltak,iIs the phase angle difference between nodes, Uk,acIs a port voltage, Ui,acIs the node voltage;
35) in the dc system, the ER port is regarded as a node equivalent power source, so the injected dc power equation is:
Figure BDA0003229792330000056
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000057
power is injected for the distributed energy source with the dc port connected to the ER,
Figure BDA0003229792330000058
active power consumed therefor, Ek、EjIs the voltage of a direct current port and a node,
Figure BDA0003229792330000059
is the mutual admittance of the direct current node;
36) writing a Jacobian matrix J of an alternating current-direct current hybrid power distribution network power flow model considering the energy router under a polar coordinate as follows:
Figure BDA00032297923300000510
in the formula:
Figure BDA00032297923300000511
active and reactive power injected into the active input port of ER,
Figure BDA00032297923300000512
for the ER ac port voltage-power control value,
Figure BDA00032297923300000513
is the phase angle of the node point,
Figure BDA00032297923300000514
is the node voltage,. DELTA.fisoFor the value of the intra-ER coordination control,
Figure BDA00032297923300000515
the injected direct-current power is supplied to the power supply,
Figure BDA00032297923300000516
direct currentBus voltage, ElIs the dc port voltage;
37) considering that the running power of the port is the same as the preset value, when the ER port adopts the fixed value
Figure BDA00032297923300000517
When controlling, the expected value of the port is used as the power value injected into the relevant node by the ER port,
Figure BDA0003229792330000061
simplifying J, obtaining
Figure BDA0003229792330000062
For the port adopting non-constant power control, the power difference value of the port change is converted into the control expression of the port through the power relation between each node and the ER port in the system, namely the above expression is used for calculation.
The method for solving the hybrid power distribution network power flow model comprises the following steps:
41) applying a Newton-Raphson method to the load flow calculation, linearizing a network equation, and expanding the power correction expression of the (n + 1) th time according to a Taylor series to obtain the following formula:
Figure BDA0003229792330000063
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000064
in order to correct the amount of correction,
Figure BDA0003229792330000065
is the sum of high-order terms of the nth iteration
Figure BDA0003229792330000066
There is an infinite term in AC networks, while in DC networks the term reduces to
Figure BDA0003229792330000067
In the formula:
Figure BDA0003229792330000068
is a differential operator;
42) performing correction calculation on the alternating current network part by a Newton-Raphson method, and performing the correction calculation on the alternating current network part
Figure BDA0003229792330000069
The simplification is performed by using only a first-order correction formula, in which case the correction is:
Figure BDA00032297923300000610
when the correction amount is calculated according to the above formula, if the initial value is not properly set, the correction amount is calculated
Figure BDA00032297923300000611
Too large and easy to make
Figure BDA00032297923300000612
Divergence;
43) introducing the self-adaptive multiplier mu into an alternating current network to obtain:
Figure BDA00032297923300000613
in the formula: mu is the coefficient of the adaptive multiplier,
when in use
Figure BDA00032297923300000614
The smaller, and mu(n)As the value of the voltage approaches 0 or 1,
Figure BDA00032297923300000615
after introducing the adaptive multiplier in the dc network,
Figure BDA0003229792330000071
truncation errors and model errors exist in the process;
the μ adaptation strategy is given, namely:
Figure BDA0003229792330000072
under the self-adaptive strategy, the obtained maximum power difference value of the (n + 1) th system is compared with the obtained maximum power difference value of the system after the correction coefficient is introduced, and the smaller one is used for corresponding
Figure BDA0003229792330000073
Make n +2 iterations, i.e.
Figure BDA0003229792330000074
Advantageous effects
Compared with the prior art, the hybrid power distribution network power flow model considering the energy router and the solving method are based on analysis of the topological structure of the AC/DC hybrid power distribution network, the AC/DC hybrid power distribution network model considering the energy router is established, an alternative iteration method considering correction step length and self-adaptive multiplier optimization with stronger adaptability is provided, and the method can be used for optimization analysis and calculation of the running state of the AC/DC hybrid power distribution network, has important theoretical significance and practical application engineering value, and is simple and convenient to obtain parameters required by calculation and strong in practicability.
Drawings
FIG. 1 is a sequence diagram of the method of the present invention;
fig. 2 is an equivalent structure diagram of an ac/dc hybrid distribution network with an energy router involved in the present invention;
FIG. 3 is a flow chart of a hybrid power distribution network power flow model and a solving algorithm according to the invention;
fig. 4 is a structure diagram of a radial hybrid power distribution network with ERs as nodes;
FIG. 5 is a structure diagram of a hand-pulled hybrid power distribution network with ER as a node;
fig. 6 is a structure diagram of a ring-shaped hybrid power distribution network with ERs as nodes.
Detailed Description
So that the manner in which the above recited features of the present invention can be understood and readily understood, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings, wherein:
as shown in fig. 1, fig. 2 and fig. 3, the hybrid power distribution network power flow model and the solving method considering the energy router according to the present invention include the following steps:
the first step, modeling of a typical structure of hybrid distribution network information: and reading the information of the hybrid power distribution network, and performing steady-state modeling on the typical structure of the hybrid power distribution network based on a Newton-Raphson method. The Newton-Raphson method converts a nonlinear equation into a linear equation, so that the load flow problem is easier to solve.
Secondly, establishing a steady-state model of the energy router: based on a hierarchical power electronic structure of the energy router, a multi-port accessed energy router steady-state model is established. The corresponding port type can be selected according to actual specific working conditions, and the flexibility of the power distribution network is enhanced. The method comprises the following specific steps:
(1) the multi-port accessed energy router steady-state model is set to comprise an alternating current port steady-state model and a direct current port steady-state model.
(2) Modeling an alternating current port steady-state model:
based on the power electronic framework of the standardized ER, if the node i is connected to the AC port of the ER, the voltage is Ui∠θiThe point corresponds to an ER newly-added node h with the alternating voltage of Uh∠θhThen δih＝δi-δh；
The reactance between node i and node h is Yih＝Gih+jBihThe port capacitance is BsiThen, the active and reactive powers injected into i are as follows:
Figure BDA0003229792330000081
in the formula:
Figure BDA0003229792330000082
the active power and the reactive power of the node i are obtained; gih，BihIs the conductance and susceptance between nodes; b issiIs a port capacitance; deltaihIs the phase angle difference between the nodes;
active power injected into node h is
Figure BDA0003229792330000083
In the formula:
Figure BDA0003229792330000091
injecting active power of the node h; gih，BihIs the conductance and susceptance between nodes; deltaihIs the phase angle difference between the nodes;
the internal losses are equivalent to the port impedance, and the power of the ER internal collection bus
Figure BDA0003229792330000092
And
Figure BDA0003229792330000093
the same;
khfor the port voltage transformation ratio, ER internal collection bus voltage EerIs composed of
Figure BDA0003229792330000094
In the formula: eerFor collecting the bus voltage, U, inside the ERhVoltage of node h, khIs the port voltage transformation ratio; the loss of the AC port satisfies
Figure BDA0003229792330000095
In the formula:
Figure BDA0003229792330000096
is the active power of the node i and,
Figure BDA0003229792330000097
and the active power of the collector bus inside the ER is injected into the port.
(3) Modeling a direct current port steady state model:
based on the direct current port in the ER, the port model is based on a DC/DC converter;
assume that the DC aggregate bus voltage with its primary side connected to ER is EkThe voltage of the secondary side connected to the DC network is El，
Figure BDA0003229792330000098
And
Figure BDA0003229792330000099
for active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio, satisfying the following:
Figure BDA00032297923300000910
in the formula: ekFor collecting the bus voltage for primary connection to ER, ElThe bus voltage is collected for dc that is primary connected to the ER,
Figure BDA00032297923300000911
and
Figure BDA00032297923300000912
for active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio;
the power loss of the branch port is the power difference between the primary side and the secondary side, and the following formula is adopted:
Figure BDA00032297923300000913
in the formula:
Figure BDA0003229792330000101
and
Figure BDA0003229792330000102
for active power on both sides of the port, EkFor collecting the bus voltage for primary connection to ER, ElFor a DC collective bus voltage primary-connected to ER, RklFor internal losses, n is the voltage transformation ratio;
if the number of the alternating current ports and the direct current ports of the ER are x and y respectively, neglecting static loss, then the operation loss delta Per,lossIs composed of
Figure BDA0003229792330000103
In the formula:
Figure BDA0003229792330000104
the loss at the ac port is reduced,
Figure BDA0003229792330000105
loss of dc port.
Step three, establishing a hybrid power distribution network power flow model: and establishing a hybrid power distribution network power flow model considering the energy router. The energy router has good functional advantages in operation, is the key for realizing the interconnection of a large-range alternating current and direct current network in the future, and the establishment of the hybrid power distribution network considering the energy router can well solve the problem of grid connection of various energy forms such as large-scale cold and heat receiving; aiming at a complex network containing an energy router, a system load flow calculation model is constructed, and certain technical support and reasonable suggestion can be provided for the overall actual planning and operation of the network. The topological structure of the energy router is more and complex, the difficulty of steady-state modeling of the energy router is increased, meanwhile, the existing energy router lacks of more comprehensive and detailed modeling analysis in the aspect of steady state, and research on an alternating current-direct current hybrid network power flow model containing the energy router is less.
The method comprises the following specific steps:
(1) and according to the established alternating current port steady-state model and the direct current port steady-state model, uniformly combining the alternating current and direct current hybrid network mathematical model with the ER to form an alternating current and direct current hybrid power distribution network power flow model considering the energy router.
(2) And carrying out load flow calculation on nodes connected with the ER by using the actual value of the mixed distribution network information.
(3) If the port number of the ER is regarded as a network virtual node, the network is divided into an alternating current network part and a direct current network part, wherein the alternating current network comprises an alternating current node of an original branch and an alternating current port equivalent node provided by the ER, and the direct current network comprises a direct current node of the original branch and a direct current port equivalent node provided by the ER;
at this time, the system power flow equation is as follows:
Figure BDA0003229792330000111
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000112
is an equation for the power of the node,
Figure BDA0003229792330000113
for ER control equation, the system waits for the electrical quantity xsIs a voltage (U)i,Uh,Eiso,El) And phase angle (theta)i,θh)。
(4) Considering the plug-and-play function of the ER for the distributed energy, the ER port is equivalent to an active input port, and the injected alternating current power equation is as follows:
Figure BDA0003229792330000114
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000115
power is injected for the VSC port of the ER and active power at the node respectively,
Figure BDA0003229792330000116
Figure BDA0003229792330000117
is the reactive power corresponding to the power value of the power,
Figure BDA0003229792330000118
for admittance between nodes, deltak,iIs the phase angle difference between nodes, Uk,acIs a port voltage, Ui,acIs the node voltage.
(5) In the dc system, the ER port is regarded as a node equivalent power source, so the injected dc power equation is:
Figure BDA0003229792330000119
in the formula (I), the compound is shown in the specification,
Figure BDA00032297923300001110
power is injected for the distributed energy source with the dc port connected to the ER,
Figure BDA00032297923300001111
active power consumed therefor, Ek、EjIs the voltage of a direct current port and a node,
Figure BDA00032297923300001112
is the transadmittance of the dc node.
(6) Writing a Jacobian matrix J of an alternating current-direct current hybrid power distribution network power flow model considering the energy router under a polar coordinate as follows:
Figure BDA0003229792330000121
in the formula:
Figure BDA0003229792330000122
active and reactive power injected into the active input port of ER,
Figure BDA0003229792330000123
for the ER ac port voltage-power control value,
Figure BDA0003229792330000124
is the phase angle of the node point,
Figure BDA0003229792330000125
is the node voltage,. DELTA.fisoFor the value of the intra-ER coordination control,
Figure BDA0003229792330000126
the injected direct-current power is supplied to the power supply,
Figure BDA0003229792330000127
DC bus voltage, ElIs the dc port voltage.
(7) Considering that the running power of the port is the same as the preset value, when the ER port adopts the fixed value
Figure BDA0003229792330000128
When controlling, the expected value of the port is used as the power value injected into the relevant node by the ER port,
Figure BDA0003229792330000129
simplifying J, obtaining
Figure BDA00032297923300001210
For the port adopting non-constant power control, the power difference value of the port change is converted into the control expression of the port through the power relation between each node and the ER port in the system, namely the above expression is used for calculation.
Fourthly, solving a hybrid power distribution network power flow model: and (4) introducing a correction step-adaptive multiplier optimization method, and solving a hybrid power distribution network power flow model based on the energy router parameters and a control mode. In the system variable correction calculation based on the Newton-Raphson method, the divergence of a variable to be calculated possibly caused by improper initial value in some environments can be caused, the step length of the correction of the substitute variable can be controlled by introducing the correction step length-adaptive multiplier, the convergence times are reduced, and the influence of system line parameters on the calculation correction process is reduced.
The method comprises the following specific steps:
(1) applying a Newton-Raphson method to the load flow calculation, linearizing a network equation, and expanding the power correction expression of the (n + 1) th time according to a Taylor series to obtain the following formula:
Figure BDA00032297923300001211
in the formula (I), the compound is shown in the specification,
Figure BDA0003229792330000131
in order to correct the amount of correction,
Figure BDA0003229792330000132
is the sum of high-order terms of the nth iteration
Figure BDA0003229792330000133
There is an infinite term in AC networks, while in DC networks the term reduces to
Figure BDA0003229792330000134
In the formula:
Figure BDA0003229792330000135
is a differential operator.
(2) Performing correction calculation on the alternating current network part by a Newton-Raphson method, and performing the correction calculation on the alternating current network part
Figure BDA0003229792330000136
The simplification is performed by using only a first-order correction formula, in which case the correction is:
Figure BDA0003229792330000137
when the correction amount is calculated according to the above formula, if the initial value is not properly set, the correction amount is calculated
Figure BDA0003229792330000138
Too large and easy to make
Figure BDA0003229792330000139
Divergence.
(3) Introducing the self-adaptive multiplier mu into an alternating current network to obtain:
Figure BDA00032297923300001310
in the formula: mu is the coefficient of the adaptive multiplier,
when in use
Figure BDA00032297923300001311
The smaller, and mu(n)As the value of the voltage approaches 0 or 1,
Figure BDA00032297923300001312
after introducing the adaptive multiplier in the dc network,
Figure BDA00032297923300001313
truncation errors and model errors exist in the process;
the μ adaptation strategy is given, namely:
Figure BDA00032297923300001314
under the self-adaptive strategy, the obtained maximum power difference value of the (n + 1) th system is compared with the obtained maximum power difference value of the system after the correction coefficient is introduced, and the smaller one is used for corresponding
Figure BDA00032297923300001315
Make n +2 iterations, i.e.
Figure BDA0003229792330000141
Based on the radial, hand-in-hand and annular mixed distribution network topology with ER as a node, the network state information is kept unchanged, and comparison tests of power flow algorithms under different load levels are performed. The method of comparative testing is as follows:
1) a standardized alternating iteration method;
2) an alternating iteration method of J is simplified by matrix features;
3) and (3) an alternative iteration method based on simplified J and correction step size-adaptive multiplier optimization.
As shown in fig. 4, 5 and 6, under three exemplary topologies, three methods are used for the calculation. Wherein, the resistance between ER-I and the node 5 is the same as that between original nodes 4-5, and the active power of each node of the direct current line is unchanged. ER-I adopts a constant direct current voltage control mode, a node 4 connected with a balanced port adopts a constant Edc,erTo fix
Figure BDA0003229792330000142
Controlling, wherein the expected values are respectively set to 1.03 and 0; the resistance between ER-II and the node 28 is the same as that between the original nodes 24-28, the nodes 4 and 24 connected with the balanced ports adopt the fixed Edc,erTo fix
Figure BDA0003229792330000143
And controlling, wherein the expected values are respectively set to 1.03 and 0, and 1.01 and 0. The ER parameter settings are shown in table 1 with a maximum reactive compensation of 50 kVar.
TABLE 1 ER parameter settings comparison table
Figure BDA0003229792330000144
TABLE 2 radial topology optimization algorithm comparisons tite、
Figure BDA0003229792330000145
Comparison table
Figure BDA0003229792330000146
Figure BDA0003229792330000151
TABLE 3 hand-hand topology optimization algorithm comparisons tite、
Figure BDA0003229792330000152
Comparison table
Figure BDA0003229792330000153
TABLE 4 comparison of ring topology optimization algorithms tite、
Figure BDA0003229792330000154
Comparison table
Figure BDA0003229792330000155
Three typical topologies are used for carrying out load flow calculation under different load levels, and the iteration times t for converging the load flow calculation is obtainediteMaximum voltage deviation from system
Figure BDA0003229792330000161
The results are shown in tables 2, 3 and 4. As can be seen from the data in the table, the invention adoptsThe three methods, namely the alternative iteration method based on the simplified J and the correction step size-adaptive multiplier optimization, keep the optimal convergence times in the test comparison. Therefore, the effectiveness of the hybrid power distribution network power flow model and the solving method considering the energy router provided by the invention is verified.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (4)

1. A hybrid power distribution network power flow model considering an energy router and a solving method are characterized by comprising the following steps:
11) modeling of a typical structure of hybrid distribution network information: reading information of the hybrid power distribution network, and performing steady-state modeling on a typical structure of the hybrid power distribution network based on a Newton-Raphson method;
12) establishing an energy router steady-state model: establishing a multi-port accessed energy router steady-state model based on a hierarchical power electronic structure of the energy router;
13) establishing a power flow model of the hybrid power distribution network: establishing a hybrid power distribution network power flow model considering an energy router;
14) solving a hybrid power distribution network power flow model: and (4) introducing a correction step-adaptive multiplier optimization method, and solving a hybrid power distribution network power flow model based on the energy router parameters and a control mode.
2. The hybrid power distribution network power flow model and solving method considering the energy router of claim 1, wherein the establishing the energy router steady state model comprises the following steps:
21) setting a multi-port accessed energy router steady-state model to comprise an alternating current port steady-state model and a direct current port steady-state model;
22) modeling an alternating current port steady-state model:
based on the power electronic framework of the standardized ER, if the node i is connected to the AC port of the ER, the voltage is Ui∠θiThe point corresponds to an ER newly-added node h with the alternating voltage of Uh∠θhThen δih＝δi-δh；
The reactance between node i and node h is Yih＝Gih+jBihThe port capacitance is BsiThen, the active and reactive powers injected into i are as follows:
Figure FDA0003229792320000011
in the formula:
Figure FDA0003229792320000012
the active power and the reactive power of the node i are obtained; gih，BihIs the conductance and susceptance between nodes; b issiIs a port capacitance; deltaihIs the phase angle difference between the nodes;
active power injected into node h is
Figure FDA0003229792320000013
In the formula:
Figure FDA0003229792320000021
injecting active power of the node h; gih，BihIs the conductance and susceptance between nodes; deltaihIs the phase angle difference between the nodes;
the internal losses are equivalent to the port impedance, and the power of the ER internal collection bus
Figure FDA0003229792320000022
And
Figure FDA0003229792320000023
the same;
khfor the port voltage transformation ratio, ER internal collection bus voltage EerIs composed of
Figure FDA0003229792320000024
In the formula: eerFor collecting the bus voltage, U, inside the ERhVoltage of node h, khIs the port voltage transformation ratio;
the loss of the AC port satisfies
Figure FDA0003229792320000025
In the formula:
Figure FDA0003229792320000026
is the active power of the node i and,
Figure FDA0003229792320000027
active power of a collecting bus inside the ER is injected into a port;
23) modeling a direct current port steady state model:
based on the direct current port in the ER, the port model is based on a DC/DC converter;
assume that the DC aggregate bus voltage with its primary side connected to ER is EkThe voltage of the secondary side connected to the DC network is El，
Figure FDA0003229792320000028
And Pl dcFor active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio, satisfying the following:
Figure FDA0003229792320000029
in the formula: ekFor collecting the bus voltage for primary connection to ER, ElThe bus voltage is collected for dc that is primary connected to the ER,
Figure FDA00032297923200000210
and Pl dcFor active power on both sides of the port, RklFor internal losses, n is the voltage transformation ratio;
the power loss of the branch port is the power difference between the primary side and the secondary side, and the following formula is adopted:
Figure FDA00032297923200000211
in the formula:
Figure FDA00032297923200000212
and Pl dcFor active power on both sides of the port, EkFor collecting the bus voltage for primary connection to ER, ElFor a DC collective bus voltage primary-connected to ER, RklFor internal losses, n is the voltage transformation ratio;
if the number of the alternating current ports and the direct current ports of the ER are x and y respectively, neglecting static loss, then the operation loss delta Per,lossIs composed of
Figure FDA0003229792320000031
In the formula:
Figure FDA0003229792320000032
the loss at the ac port is reduced,
Figure FDA0003229792320000033
loss of dc port.
3. The hybrid power distribution network flow model and solving method considering the energy router of claim 1, wherein the establishment of the hybrid power distribution network flow model comprises the following steps:
31) according to the established alternating current port steady-state model and the established direct current port steady-state model, an alternating current and direct current hybrid network mathematical model and an ER are combined together in a unified mode to form an alternating current and direct current hybrid power distribution network power flow model considering the energy router;
32) carrying out load flow calculation on nodes connected with ER by using the actual value of the mixed distribution network information;
33) if the port number of the ER is regarded as a network virtual node, the network is divided into an alternating current network part and a direct current network part, wherein the alternating current network comprises an alternating current node of an original branch and an alternating current port equivalent node provided by the ER, and the direct current network comprises a direct current node of the original branch and a direct current port equivalent node provided by the ER;
at this time, the system power flow equation is as follows:
Figure FDA0003229792320000034
in the formula (I), the compound is shown in the specification,
Figure FDA0003229792320000035
is an equation for the power of the node,
Figure FDA0003229792320000036
for ER control equation, the system waits for the electrical quantity xsIs a voltage (U)i,Uh,Eiso,El) And phase angle (theta)i,θh)；
34) Considering the plug-and-play function of the ER for the distributed energy, the ER port is equivalent to an active input port, and the injected alternating current power equation is as follows:
Figure FDA0003229792320000037
in the formula (I), the compound is shown in the specification,
Figure FDA0003229792320000038
power is injected for the VSC port of the ER and active power at the node respectively,
Figure FDA0003229792320000039
Figure FDA0003229792320000041
is the reactive power corresponding to the power value of the power,
Figure FDA0003229792320000042
for admittance between nodes, deltak,iIs the phase angle difference between nodes, Uk,acIs a port voltage, Ui,acIs the node voltage;
35) in the dc system, the ER port is regarded as a node equivalent power source, so the injected dc power equation is:
Figure FDA0003229792320000043
in the formula (I), the compound is shown in the specification,
Figure FDA0003229792320000044
power is injected for the distributed energy source with the dc port connected to the ER,
Figure FDA0003229792320000045
active power consumed therefor, Ek、EjIs the voltage of a direct current port and a node,
Figure FDA0003229792320000046
is the mutual admittance of the direct current node;
36) writing a Jacobian matrix J of an alternating current-direct current hybrid power distribution network power flow model considering the energy router under a polar coordinate as follows:
Figure FDA0003229792320000047
in the formula:
Figure FDA0003229792320000048
active and reactive power injected into the active input port of ER,
Figure FDA0003229792320000049
for the ER ac port voltage-power control value,
Figure FDA00032297923200000410
is the phase angle of the node point,
Figure FDA00032297923200000411
is the node voltage,. DELTA.fisoFor the value of the intra-ER coordination control,
Figure FDA00032297923200000412
the injected direct-current power is supplied to the power supply,
Figure FDA00032297923200000413
DC bus voltage, ElIs the dc port voltage;
37) considering that the running power of the port is the same as the preset value, when the ER port adopts the fixed Pi acWhen controlling, the expected value of the port is used as the power value injected into the relevant node by the ER port,
Figure FDA00032297923200000414
simplifying J, obtaining
Figure FDA00032297923200000415
For the port adopting non-constant power control, the power difference value of the port change is converted into the control expression of the port through the power relation between each node and the ER port in the system, namely the above expression is used for calculation.
4. The hybrid power distribution network power flow model and solving method considering energy routers, according to claim 1, wherein the solving of the hybrid power distribution network power flow model comprises the following steps:
41) applying a Newton-Raphson method to the load flow calculation, linearizing a network equation, and expanding the power correction expression of the (n + 1) th time according to a Taylor series to obtain the following formula:
Figure FDA0003229792320000051
in the formula (I), the compound is shown in the specification,
Figure FDA0003229792320000052
in order to correct the amount of correction,
Figure FDA0003229792320000053
is the sum of high-order terms of the nth iteration
Figure FDA0003229792320000054
There is an infinite term in AC networks, while in DC networks the term reduces to
Figure FDA0003229792320000055
In the formula:
Figure FDA0003229792320000056
is a differential operator;
42) performing correction calculation on the alternating current network part by a Newton-Raphson method, and performing the correction calculation on the alternating current network part
Figure FDA0003229792320000057
Performing a simplification using only first order correctionsThe correction amount is:
Figure FDA0003229792320000058
when the correction amount is calculated according to the above formula, if the initial value is not properly set, the correction amount is calculated
Figure FDA0003229792320000059
Too large and easy to make
Figure FDA00032297923200000510
Divergence;
43) introducing the self-adaptive multiplier mu into an alternating current network to obtain:
Figure FDA00032297923200000511
in the formula: mu is the coefficient of the adaptive multiplier,
when in use
Figure FDA00032297923200000512
The smaller, and mu(n)As the value of the voltage approaches 0 or 1,
Figure FDA00032297923200000513
after introducing the adaptive multiplier in the dc network,
Figure FDA00032297923200000514
truncation errors and model errors exist in the process;
the μ adaptation strategy is given, namely:
Figure FDA0003229792320000061
under the self-adaptive strategy, the obtained maximum power difference value of the (n + 1) th system is compared with the obtained maximum power difference value of the system after the correction coefficient is introduced, and the smaller one is used for corresponding
Figure FDA0003229792320000062
Make n +2 iterations, i.e.
Figure FDA0003229792320000063
CN202110983514.3A 2021-08-25 2021-08-25 Hybrid power distribution network power flow model considering energy router and solving method Pending CN113690892A (en)

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