CN111835011A - Power distribution network load flow calculation method - Google Patents
Power distribution network load flow calculation method Download PDFInfo
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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
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- G—PHYSICS
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
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- G06F30/36—Circuit design at the analogue level
- G06F30/367—Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/04—Power grid distribution networks
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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
- 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]
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Abstract
The invention relates to a power distribution network load flow calculation method, which comprises the following steps: the power distribution network model comprises a power distribution network model and a power distribution transformer model; carrying out load flow calculation from the tail end to the head end bus by using a branch loss method, calculating voltage drop section by section from the tail end according to given head end voltage and the obtained head end power, obtaining each node voltage, deducing section by section from the tail end node voltage and the load power obtained, and repeating the process until the voltage deviation of each node meets the convergence condition; through load flow calculation, the impedance parameters of each main line and each branch circuit and related parameters of the transformer are known, so that the voltage of each node and the voltage current conforming to the branch circuit are calculated; the invention has the advantages of convenient calculation, multiple and accurate calculation points.
Description
Technical Field
The invention relates to the technical field of operation analysis of power systems, in particular to a power distribution network load flow calculation method.
Background
And (3) power distribution network load flow calculation: the electric state of the whole network is determined according to the structure and the operation condition of a given network, the voltage amplitude and the phase angle of each node, the power distribution and the power loss in the network are mainly used for mastering the operation state of a power distribution system, and a power flow calculation algorithm of the power distribution network mainly comprises a forward-backward substitution method, an improved Newton method, a loop impedance method and an implicit Zbus Gaussian method; the load flow calculation of the power distribution network needs the support of the automation of the power distribution network, the impedance parameters of each main line and each branch line and the related parameters of a transformer are known, and the voltage and the current of each node voltage and a load branch are known, but the existing algorithm (such as a pq decomposition method) which is effective in the high-voltage power transmission network is sometimes ineffective in the power distribution network due to the large ratio (r/x) of the resistance to the reactance of the parameters of the power distribution network, and reliable convergence can not be realized, and the three-phase voltage and the current of the power distribution network are not symmetrical due to the existence of a large number of unbalanced loads in the power distribution network and the adoption of a mixed power supply mode of single-phase lines and three-; therefore, it is very necessary to provide a power distribution network load flow calculation method which is convenient to calculate, has many calculation points and is accurate.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides the power distribution network load flow calculation method which is convenient to calculate, has multiple calculated points and is accurate.
The purpose of the invention is realized as follows: a power distribution network load flow calculation method comprises the following steps:
step 1): the distribution network model comprises a distribution line model and a distribution transformer model, for the distribution line model, as the distribution line is not more than dozens of kilometers, the line admittance is ignored, and for the distribution transformer model, a T-type or pi-type equivalent circuit is adopted;
step 2): carrying out load flow calculation from the tail end to the head end bus by using a branch circuit loss method, calculating from the tail end to the head end at the beginning, setting the voltage of the whole network as rated voltage, deducing from the tail end to the head end section by section according to load power, calculating only power loss in each element without calculating voltage, solving current and power loss on each branch circuit, and obtaining head end power according to the current and power loss, which is a back generation process; calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section to obtain each node voltage, which is a forward process;
step 3): and (4) performing iterative calculation, gradually deducing to the head end according to the obtained voltage and load power of the tail end node, and repeating the process until the voltage deviation of each node meets the convergence condition.
Step 2), calculating the head end power in the back substitution process:
Sb”＝Sc+ΔSc
Sb'＝Sb”+Sb
in the formula Rc+jXcIs c point impedance, PcIs c point active power, QcIs reactive power at point c, ScAnd SbThe apparent powers of the node a and the node 0 are obtained in the same manner as the apparent powers of the node c and the node ba’And So。
Step 2) voltage calculation in the forward process, calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section, and obtaining the voltage of each node
Ua＝U0-ΔUa
Determining the voltage U of the node b and the node cbAnd Uc。
Iterative calculation process in step 3): the voltage of the terminal c node is Uc, and the second step back substitution process is carried out to obtain the head end power; then, the third step of forward process is carried out to obtain the voltage of each node until the voltage of each node meets the convergence condition, namely the condition is met
The invention has the beneficial effects that: the invention provides a power distribution network load flow calculation method, which comprises the following steps: the power distribution network model comprises a power distribution network model and a power distribution transformer model; carrying out load flow calculation from the tail end to the head end bus by using a branch loss method, calculating voltage drop section by section from the tail end according to given head end voltage and the obtained head end power, obtaining each node voltage, deducing section by section from the tail end node voltage and the load power obtained, and repeating the process until the voltage deviation of each node meets the convergence condition; through load flow calculation, the impedance parameters of each main line and each branch circuit and related parameters of the transformer are known, so that the voltage of each node and the voltage current conforming to the branch circuit are calculated; the invention has the advantages of convenient calculation, multiple and accurate calculation points.
Drawings
FIG. 1 is a flow chart of the algorithm of the present invention.
Fig. 2 is an equivalent mathematical circuit diagram of the short circuit of the present invention.
FIG. 3 is a T-shaped equivalent circuit diagram of the present invention.
Fig. 4 is a 4-node open loop leg diagram of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Example 1
A power distribution network load flow calculation method comprises the following steps:
step 1): the distribution network model comprises a distribution line model and a distribution transformer model, for the distribution line model, as the distribution line is not more than dozens of kilometers, the line admittance is ignored, and for the distribution transformer model, a T-type or pi-type equivalent circuit is adopted;
step 2): carrying out load flow calculation from the tail end to the head end bus by using a branch circuit loss method, calculating from the tail end to the head end at the beginning, setting the voltage of the whole network as rated voltage, deducing from the tail end to the head end section by section according to load power, calculating only power loss in each element without calculating voltage, solving current and power loss on each branch circuit, and obtaining head end power according to the current and power loss, which is a back generation process; calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section to obtain each node voltage, which is a forward process;
step 3): and (4) performing iterative calculation, gradually deducing to the head end according to the obtained voltage and load power of the tail end node, and repeating the process until the voltage deviation of each node meets the convergence condition.
The invention provides a power distribution network load flow calculation method, which comprises the following steps: the power distribution network model comprises a power distribution network model and a power distribution transformer model; carrying out load flow calculation from the tail end to the head end bus by using a branch loss method, calculating voltage drop section by section from the tail end according to given head end voltage and the obtained head end power, obtaining each node voltage, deducing section by section from the tail end node voltage and the load power obtained, and repeating the process until the voltage deviation of each node meets the convergence condition; through load flow calculation, the impedance parameters of each main line and each branch circuit and related parameters of the transformer are known, so that the voltage of each node and the voltage current conforming to the branch circuit are calculated; the invention has the advantages of convenient calculation, multiple and accurate calculation points.
Example 2
Step 1): the distribution network model comprises a distribution line model and a distribution transformer model, for the distribution line model, as the distribution line is not more than dozens of kilometers, the line admittance is ignored, and for the distribution transformer model, a T-type or pi-type equivalent circuit is adopted;
step 2): carrying out load flow calculation from the tail end to the head end bus by using a branch circuit loss method, calculating from the tail end to the head end at the beginning, setting the voltage of the whole network as rated voltage, deducing from the tail end to the head end section by section according to load power, calculating only power loss in each element without calculating voltage, solving current and power loss on each branch circuit, and obtaining head end power according to the current and power loss, which is a back generation process; calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section to obtain each node voltage, which is a forward process;
step 3): and (4) performing iterative calculation, gradually deducing to the head end according to the obtained voltage and load power of the tail end node, and repeating the process until the voltage deviation of each node meets the convergence condition.
For the distribution line, since the distribution line generally does not exceed several tens of kilometers, the line admittance is generally neglected, and the structure shown in fig. 2 below can be adopted.
For distribution transformers, T-type or pi-type equivalent circuits are commonly used, as shown in fig. 3.
Take the 4-node open-loop leg shown in fig. 4 as an example. Suppose that the bus voltage U from the 0 node of the head end bus is known0And end node power SC。
(1) First assume that each node voltage is equal to its nominal voltage,
namely: uc ═ Ub ═ Ua ═ Un
(2) Carrying out a back substitution process: and solving the current and power loss on each branch circuit, and obtaining the head end power according to the current and power loss.
And (3) power calculation:
Sb”＝Sc+ΔSc
Sb'＝Sb”+Sb
similar calculation of the power S of the a node and the 0 nodea’And S0。
(3) Carrying out a forward pushing process: and calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section to obtain the voltage of each node.
And (3) voltage calculation:
Ua＝U0-ΔUa
analogous determination of the voltages U at the b-node and the c-nodebAnd Uc。
(4) And (3) iterative calculation: and deducing from the head end section by section according to the obtained voltage and load power of the tail end node.
Assuming that the voltage of the c node at the tail end is Uc, carrying out the second step back substitution process to obtain the power of the head end; and then carrying out the third step of forward pushing process to obtain the pressure of each node. Until the node voltages meet the convergence condition.
The invention provides a power distribution network load flow calculation method, which comprises the following steps: the power distribution network model comprises a power distribution network model and a power distribution transformer model; carrying out load flow calculation from the tail end to the head end bus by using a branch loss method, calculating voltage drop section by section from the tail end according to given head end voltage and the obtained head end power, obtaining each node voltage, deducing section by section from the tail end node voltage and the load power obtained, and repeating the process until the voltage deviation of each node meets the convergence condition; through load flow calculation, the impedance parameters of each main line and each branch circuit and related parameters of the transformer are known, so that the voltage of each node and the voltage current conforming to the branch circuit are calculated; the invention has the advantages of convenient calculation, multiple and accurate calculation points.
Claims (4)
1. A power distribution network load flow calculation method is characterized by comprising the following steps: it comprises the following steps:
step 1): the distribution network model comprises a distribution line model and a distribution transformer model, for the distribution line model, as the distribution line is not more than dozens of kilometers, the line admittance is ignored, and for the distribution transformer model, a T-type or pi-type equivalent circuit is adopted;
step 2): carrying out load flow calculation from the tail end to the head end bus by using a branch circuit loss method, calculating from the tail end to the head end at the beginning, setting the voltage of the whole network as rated voltage, deducing from the tail end to the head end section by section according to load power, calculating only power loss in each element without calculating voltage, solving current and power loss on each branch circuit, and obtaining head end power according to the current and power loss, which is a back generation process; calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section to obtain each node voltage, which is a forward process;
step 3): and (4) performing iterative calculation, gradually deducing to the head end according to the obtained voltage and load power of the tail end node, and repeating the process until the voltage deviation of each node meets the convergence condition.
2. The power flow calculation method for the power distribution network according to claim 1, wherein: calculating the head end power in the step 2) back-substitution process:
Sb”＝Sc+ΔSc
Sb'＝Sb”+Sb
in the formula Rc+jXcIs c point impedance, PcIs c point active power, QcIs reactive power at point c, ScAnd SbThe apparent powers of the node a and the node 0 are obtained in the same manner as the apparent powers of the node c and the node ba’And So。
3. The power flow calculation method for the power distribution network according to claim 1, wherein: step 2) voltage calculation in the forward process, calculating voltage drop from the given head end voltage and the obtained head end power to the tail end section by section, and obtaining the voltage of each node
Ua＝U0-ΔUa
Determining the voltage U of the node b and the node cbAnd Uc。
4. The power flow calculation method for the power distribution network according to claim 1, wherein: the iterative calculation process in the step 3): the voltage of the terminal c node is Uc, and the second step back substitution process is carried out to obtain the head end power; then, the third step of forward process is carried out to obtain the voltage of each node until the voltage of each node meets the convergence condition, namely the condition is met
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113037331A (en) * | 2021-03-04 | 2021-06-25 | 电子科技大学成都学院 | Carrier information enhancement method used between interactive devices in power distribution network |
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Patent Citations (4)
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| CN103632052A (en) * | 2013-11-27 | 2014-03-12 | 国网上海市电力公司 | Power distribution network load flow calculation method |
| CN103928925A (en) * | 2014-04-17 | 2014-07-16 | 国家电网公司 | Power distribution network load flow calculation method based on forward-backward sweep |
| EP3098924A1 (en) * | 2015-05-29 | 2016-11-30 | Electricité de France | A method and device for calculation of power flow in the distribution grid |
| CN107069739A (en) * | 2017-02-15 | 2017-08-18 | 河海大学 | A kind of distribution power system load flow calculation method based on forward-backward sweep method |
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| CN113037331A (en) * | 2021-03-04 | 2021-06-25 | 电子科技大学成都学院 | Carrier information enhancement method used between interactive devices in power distribution network |
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