CN114221352A - Voltage coordination control method based on reactive power-active power network loss partition set domain - Google Patents

Voltage coordination control method based on reactive power-active power network loss partition set domain Download PDF

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CN114221352A
CN114221352A CN202111500839.8A CN202111500839A CN114221352A CN 114221352 A CN114221352 A CN 114221352A CN 202111500839 A CN202111500839 A CN 202111500839A CN 114221352 A CN114221352 A CN 114221352A
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李�赫
谭为先
曹志刚
李继东
丁仁杰
葛津铭
王振浩
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Jilin Ruilai Technology Development Co ltd
Tongliao Power Supply Co Of State Grid East Inner Mongolia Electric Power Co
State Grid Corp of China SGCC
Northeast Electric Power University
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Tongliao Power Supply Co Of State Grid East Inner Mongolia Electric Power Co
State Grid Corp of China SGCC
Northeast Dianli University
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Abstract

A voltage coordination control method based on a reactive power-active power network loss partition set domain belongs to the technical field of analysis, operation and control of power systems. The invention aims to provide a voltage coordination control method based on a reactive power-active power loss partition set domain, which carries out reactive power-voltage sensitivity weight partition and active power loss-voltage sensitivity weight partition on a system according to a modularity function model, provides a concept of a set domain, and carries out set domain partition rationality judgment by utilizing the provided reactive support capability index. The method comprises the following steps: the method comprises the steps of calculating reactive power-voltage and active network loss-voltage sensitivity, establishing a modularity function model based on the weight of the sensitivity, establishing a reactive support capability index, and partitioning an electric power system network containing N nodes by using the improved modularity function model. The set domain reactive power supporting capability index provided by the invention ensures the regulation and control capability of the adjustable reactive power compensation device in the subarea on the voltage of the load node, and quickly judges the subarea rationality.

Description

Voltage coordination control method based on reactive power-active power network loss partition set domain
Technical Field
The invention belongs to the technical field of analysis, operation and control of power systems.
Background
With the rapid development of the power industry, the power network in China has become one of the most large-scale and most complex-hierarchy network systems in the world. The study on the complex layered distribution structure and the strong coupling of the power network further solves the problems of ultra-large-scale power grid security monitoring and optimization control under the new situation, and is a difficult point and a hotspot of the current power system study. Reactive voltage control is an important component of power grid safety control, and has important significance for ensuring the stability and the economy of system operation. With the gradual increase of the scale of the power grid, the reactive power partitioning of the power grid is increasingly important according to certain rules by utilizing the reactive local balance characteristic.
In the existing research, the main methods for solving the problems of reactive power shortage and node voltage out-of-limit without changing the power grid structure are as follows: adjusting transformer taps, limiting active power, installing reactors, etc. However, as more and more widely distributed new energy power generation systems are accessed, the number of control nodes in the system is increased, and if the method is continuously adopted, the active network loss is increased, and even the real-time performance of the control mode is affected. By utilizing the characteristic of reactive compensation local balance, the system needs to be partitioned into nodes urgently, the search range of the reactive compensation device is narrowed, and reactive-voltage accurate adjustment is carried out. The node partition is divided based on the characteristics of the partition, and is characterized in that: nodes inside the region are strongly coupled, and nodes outside the region are weakly coupled. Thereby forming a partitioned work group with the inside capable of independently operating and the outside capable of mutually coordinating. The current partitioning method comprises the following steps: 1) the method comprises the steps of using a user to specify a clustering-based K mean algorithm of partition number, using a community network mining method, using a distribution network structure graph theory method and the like, wherein the methods do not consider the problem of reactive local balance. 2) The multi-target algorithm for partitioning is as follows: the method comprises the steps of performing partition optimization on an incoming line high-voltage distribution network by using an upper-layer partition improved multi-objective optimization algorithm and a lower-layer partition improved multi-objective optimization algorithm and a 3-stage heuristic optimization algorithm, and the like, wherein the algorithms do not relate to the increased active network loss caused by reactive power regulation in a system.
Disclosure of Invention
The invention aims to provide a voltage coordination control method based on a reactive power-active power loss partition set domain, which carries out reactive power-voltage sensitivity weight partition and active power loss-voltage sensitivity weight partition on a system according to a modularity function model, provides a concept of a set domain, and carries out set domain partition rationality judgment by utilizing the provided reactive support capability index.
The method comprises the following steps:
s1, calculation of reactive power-voltage and active network loss-voltage sensitivity
Assuming that the total number of nodes is N, including the reactive node set { G } and the load nodes { L } that can provide reactive power, the system includes the control model of the above nodes as follows:
Figure BDA0003401563890000011
where H, N, J, L are the elements in the control matrix,ΔQGfor reactive node reactive power variation, Δ QLFor load node reactive power variation, Δ UGFor the magnitude change of the voltage of the reactive node, Δ ULIs the voltage variation of the load node;
if the node is both a reactive node and a load node, the formula (1) is:
[ΔQG]＝[HGG LLL][ΔUL] (2)
assuming the injected reactive power at the load node is unchanged, i.e.: delta QLEliminating the reactive node voltage variation Δ U by equation (1) when it is 0GAnd obtaining a sensitivity expression between the unit voltage amplitude of the load i node and the reactive variable quantity of the reactive j node as follows:
Figure BDA0003401563890000021
the node voltage amplitude variation is expressed as:
ΔU＝SQU,ijΔQ (4)
in a network with the number of nodes being N, the system active network loss-voltage relationship is expressed as follows:
Figure BDA0003401563890000022
the sensitivity of the whole network active network loss to reactive power is represented by using differential, and the sensitivity is rewritten into a matrix form:
Figure BDA0003401563890000023
the sensitivity expression of the system network loss to the node power change is as follows:
Figure BDA0003401563890000024
since the reactive power change directly affects the voltage change, equations (8) to (9) are satisfied:
Figure BDA0003401563890000025
Figure BDA0003401563890000026
the active network loss-voltage sensitivity expression obtained according to the formulas (7) and (9) is as follows:
Figure BDA0003401563890000027
s2 sensitivity-based weighting
And weighting the reactive-voltage sensitivity to obtain:
w＝SQU,ij·Qi,j (11)
wherein:
Figure BDA0003401563890000028
in the formula: sQU,ijIs the reactive-voltage sensitivity between the i node and the j node; qi,j,1Representing reactive power, Q, of the input line from the head endi,j,2Indicating reactive power, S, of the end outgoing lineQU,ijThe smaller the voltage influence of the reactive node on the load node, Qi,jThe smaller the reactive power transmitted between the node i and the node j is, the same weight is given to the node i and the node j;
using an electrical matrix of impedances, element d of the matrixijExpressed as:
dij＝zii+zjj-zij-zji (13)
the electrical distance matrix is obtained by simplifying the node impedance matrix:
Figure BDA0003401563890000031
the active network loss-voltage sensitivity weight expression is:
wij＝SPlossU,ij·dij (15)
in the formula, SijFor active network loss-voltage sensitivity, dijIs the electrical distance between node i and node j, which is an element in the electrical distance matrix, SijSmaller represents a smaller link between the active network loss and the line ij, dijThe smaller the electrical distance between the node i and the node j is, the same weight is given to the node i and the node j;
s3, establishing a modularity function model
The modularity function formula is defined as follows:
Figure BDA0003401563890000032
wherein: a. theijIs a connecting line between the node i and the node j, if the node i is connected with the node j, A ij1, otherwise Aij0, according to AijThe characteristic of (A) is that the connection matrix without phase diagram is a symmetrical matrix along the main diagonal, namely Aij＝AjiIf the node i and the node j are in the same partition, the delta function is 1, otherwise, delta (i, j) is 0;
Figure BDA0003401563890000033
m represents the sum of all weights in the network:
Figure BDA0003401563890000034
and improving the modularity function, wherein the improved modularity function is as follows:
Figure BDA0003401563890000035
wherein A isijIs a weight sensitivity value, i.e. Aij＝wijThen k isiRepresenting the sum of all weights connected to node i, i.e.：
Figure BDA0003401563890000036
Calculating a modularity function by using the weight indexes, representing the weight coupling degrees among different nodes, and partitioning the nodes with different coupling degrees;
s4, establishing reactive support capability index
The reactive support capability index is expressed as:
Figure BDA0003401563890000041
wherein QiFor the total reactive power compensation capacity in a zone, i.e. the sum of the maximum reactive output capacities of all reactive power compensation devices in a zone, QqConsidering maximum load and power flow in the subarea, considering that the subarea has enough reactive power when K is more than or equal to 15-20%, the subarea is suitable, when K is more than or equal to 15-20%<When the percentage of the total power is 15%, the reactive power in the subareas is considered to be insufficient;
s5, for the power system network containing N nodes, the partitioning step by using the improved modularity function model is as follows:
(1) initializing each node of the power system, and calculating an improved modularity function by taking each node as an independent sub-partition;
(2) for the node i, randomly selecting a node j from the nodes connected with the node i to calculate improved modularity, selecting a new partition with the largest calculated value, and updating the improved modularity;
(3) repeating the step 2 for the new partition until all nodes in the power system are traversed;
(4) stopping partitioning when no new partition is divided or the improved modularity calculation value reaches the maximum;
(5) respectively marking out a reactive power-voltage sensitivity subarea and an active power network loss-voltage sensitivity subarea by the steps;
s6 partition voltage control strategy
The minimum reactive power adjustment quantity meeting the out-of-limit voltage standard in the set domain is represented as:
Figure BDA0003401563890000042
wherein, U in the formulai max、Ui minUpper and lower limits of the node voltage, U, respectivelyiIs the i node voltage, Si,iIs the self reactive-voltage sensitivity at the i-node.
The invention has the advantages that:
the main advantages of this patent have following several:
1. and only the reactive node and the load node of the power system are extracted in the solving process by adopting reactive power-voltage sensitivity and active network loss-voltage sensitivity. The solving step is simplified.
2. The weight analysis based on the two sensitivities has the advantage that the weight is used as a judgment standard, and the importance of the reactive compensation node and the load node is displayed. More accurate and objective.
3. A modularity function model is established, the modularity function is calculated by using the solved weight indexes, the coupling degrees among different nodes can be represented, and the nodes with different coupling degrees are partitioned. The inner part of the subarea is more compact, and the outer part is more independent.
4. The provided reactive power supporting capability index of the collective domain ensures the regulation and control capability of the adjustable reactive power compensation device in the subarea to the voltage of the load node. And quickly judging the partition rationality.
5. The provided zone voltage control strategy not only considers the reactive compensation capability of the reactive compensation device on the node, but also considers the problem of the increase of the active network loss caused by the improvement of the voltage. The voltage regulation and the network loss reduction are cooperatively considered.
Drawings
FIG. 1 is a schematic diagram of the set domain partitioning step of the present invention;
FIG. 2 is a flow chart of the zone voltage control of the present invention;
FIG. 3 is a system diagram of the present invention;
FIG. 4 is a reactive-voltage sensitivity weight partition diagram of the present invention;
fig. 5 is a graph of active network loss-voltage sensitivity weight zoning in accordance with the present invention;
FIG. 6 is a set domain partition diagram of the present invention;
FIG. 7 is a graph comparing node voltages according to the present invention.
Detailed Description
Aiming at the voltage stability problem of the power system, the invention researches a voltage coordination control strategy based on a reactive power-voltage sensitivity weight partition and an active network loss-voltage sensitivity weight partition. The control strategy aims at controlling the stability of the out-of-limit node voltage of the system, firstly, according to a modularity function model, the system is subjected to reactive power-voltage sensitivity weight partitioning and active network loss-voltage sensitivity weight partitioning, and a concept of a set domain is provided; and then, carrying out set domain partition rationality judgment by using the provided reactive support capability index, providing a partition voltage control strategy, providing reactive support for a voltage control point by using a node in a set domain, and finally realizing optimal rational control on a voltage limit-exceeding point.
When the control variable changes, the output variable of the system changes as the control variable changes, and this change is expressed in the form of the differential of the control variable and the output variable, which is called sensitivity.
In the power system, when sensitivity division is carried out on the power system according to a Jacobian matrix calculated according to power flow of the power system, the strong correlation between reactive power and voltage is considered, and the influence of active power change on the voltage is usually not considered. Only reactive voltage control is performed on the power system. However, due to the length of the transmission line, the active power consumed by the whole network cannot be ignored when performing reactive compensation to improve the voltage level. Therefore, from the sensitivity perspective of the power system, the reactive-voltage sensitivity weight and the active network loss-voltage sensitivity weight are calculated, and the system is partitioned according to the modularity function model.
The method comprises the following steps: and (4) solving the reactive power-voltage and active network loss-voltage sensitivity.
The system control model proposed herein based on the power system load flow calculation model is as follows. Because the voltage amplitude changes, the reactive power coupling degree is higher, and the active power coupling degree is lower, the total number of the nodes is set to be N, the reactive node set { G } and the load node { L } which can provide reactive power are contained, and the control model of the system containing the nodes is as follows:
Figure BDA0003401563890000051
wherein H, N, J, L are the elements in the control matrix, respectively, Δ QGFor reactive node reactive power variation, Δ QLFor load node reactive power variation, Δ UGFor the magnitude change of the voltage of the reactive node, Δ ULIs the load node voltage variation.
In a special case, if the node is both a reactive node and a load node, equation (1) may be changed as follows:
[ΔQG]＝[HGG LLL][ΔUL] (2)
assuming the injected reactive power at the load node is unchanged, i.e.: delta QL0. Eliminating the voltage variation Delta U of the reactive node by the formula (1)GAnd the sensitivity expression between the unit voltage amplitude of the obtained load i node and the reactive variable quantity of the reactive j node is as follows:
Figure BDA0003401563890000061
the node voltage magnitude change can be expressed as:
ΔU＝SQU,ijΔQ (4)
and solving the active network loss-voltage sensitivity in order to reflect the index of the change of the active network loss along with the load. In a network with the number of nodes N, the system active network loss-voltage relationship can be expressed as:
Figure BDA0003401563890000062
the sensitivity of the whole network active network loss to reactive power is represented by using differential, and the sensitivity is rewritten into a matrix form:
Figure BDA0003401563890000063
according to a Newton-Raphson method load flow calculation formula and a Jacobian matrix calculation formula, the sensitivity expression of system network loss to node power change is obtained as follows:
Figure BDA0003401563890000064
since a reactive power change can directly affect a voltage change, equations (8) to (9) are satisfied:
Figure BDA0003401563890000065
Figure BDA0003401563890000066
the expressions of the loss-voltage sensitivity of the active network obtained according to the expressions (7) and (9) are as follows:
Figure BDA0003401563890000067
step two: sensitivity-based weight analysis
When the power system operates in a steady state, the node voltage is greatly influenced by the reactive power of the system. The sensitivity of the reactive compensation node represents the adjusting capacity of the voltage out-of-limit node, and the weight represents the relative importance of the index. Therefore, the importance of the compensation node is more objectively displayed by taking the weight of the node as a judgment standard, namely, the importance is higher when the weight of the node is higher.
The above reactive-voltage sensitivity is subjected to weight analysis to obtain:
w＝SQU,ij·Qi,j (11)
wherein:
Figure BDA0003401563890000071
in the formula: sQU,ijIs the reactive-voltage sensitivity between the i node and the j node; qi,j,1Representing reactive power, Q, of the input line from the head endi,j,2Representing the reactive power of the end outgoing line. SQU,ijThe smaller the voltage influence of the reactive node on the load node, Qi,jSmaller represents less reactive power transferred between the i node and the j node, both having the same weight.
Analyzing the active network loss-voltage sensitivity, and adopting an impedance electric matrix in which an element d is arranged to better reflect the relation between the active network loss and a lineijExpressed as:
dij＝zii+zjj-zij-zji (13)
the electrical distance matrix can be obtained by simplifying the node impedance matrix:
Figure BDA0003401563890000072
the active network loss-voltage sensitivity weight expression is:
wij＝SPlossU,ij·dij (15)
in the formula, SijFor active network loss-voltage sensitivity, dijIs the electrical distance between node i and node j, which is an element in the electrical distance matrix. SijSmaller represents a smaller link between the active network loss and the line ij, dijSmaller means smaller electrical distance between node i and node j, both having the same weight.
When the operation mode of the system is changed, the line weight is changed, and the reactive-voltage sensitivity weight and the active network loss-voltage sensitivity weight need to be recalculated.
Step three: establishing a modularity function model
In order to solve the partitioning problem of the complex network, an optimal partitioning result is directly formed, a modularity function model is introduced, and a modularity function formula is defined as follows:
Figure BDA0003401563890000073
wherein A isijIs a connecting line between the node i and the node j, if the node i is connected with the node j, Aij1, otherwise Aij0. According to AijThe characteristic of (A) is that the connection matrix without phase diagram is a symmetrical matrix along the main diagonal, namely Aij＝Aji. If node i is in the same partition as node j, the δ function is 1, otherwise δ (i, j) is 0.
kiRepresents the sum of all weights connected to inodes:
Figure BDA0003401563890000081
m represents the sum of all weights in the network:
Figure BDA0003401563890000082
according to the above weight analysis, the modularity function is improved, and the improved modularity function is as follows:
Figure BDA0003401563890000083
wherein A isijIs a weight sensitivity value, i.e. Aij＝wij. Then k isiRepresents the sum of all weights connected to node i, i.e.:
Figure BDA0003401563890000084
and calculating a modularity function by using the weight indexes, representing the weight coupling degree among different nodes, and partitioning the nodes with different coupling degrees.
Step four: and establishing a reactive support capability index.
For the power network partitioned by the improved modularity function, the coupling degree between different nodes can be represented by a network structure. In order to guarantee the regulation and control capability of the adjustable reactive power compensation device in the subarea on the voltage of the load node, the condition that the reactive power in the subarea is insufficient or excessive is avoided. According to a power margin coefficient (active margin coefficient) frequently adopted in engineering, an index of reactive power supporting capacity in a subarea is provided to meet the reactive power regulating capacity of the subarea device. The reactive support capability index may be expressed as:
Figure BDA0003401563890000085
wherein QiThe total reactive power compensation capacity in the subarea is the sum of the maximum reactive power output capacities of all the reactive power compensation devices in the subarea. QqIs the reactive load within the partition. Considering the maximum load and the power flow in the subarea, when the K is more than or equal to 15-20%, the subarea is suitable if the reactive power in the subarea is sufficient. When K is<At 15%, the partition is deemed to have insufficient reactive power.
Step five: and realizing weight partition based on modularity. For a power system network containing N nodes, partitioning by using an improved modularity function model comprises the following steps:
(1) initializing each node of the power system, and calculating an improved modularity function by taking each node as an independent sub-partition;
(2) for the node i, randomly selecting a node j from the nodes connected with the node i to calculate improved modularity, selecting a new partition with the largest calculated value, and updating the improved modularity;
(3) repeat step 2 for the new partition. Traversing all nodes in the power system;
(4) stopping partitioning when no new partition is divided or the improved modularity calculation value reaches the maximum;
(5) and respectively marking out a reactive power-voltage sensitivity subarea and an active power network loss-voltage sensitivity subarea by the steps.
Step six: partition voltage control strategy
In the present invention, the results of the division of reactive-voltage sensitivity weights and division of active grid loss-voltage sensitivity weights can be obtained from the above-defined and improved modularity function model. In the reactive power control strategy of the patent, in order to maximize the utilization of reactive power compensation equipment, a cooperative consideration strategy of a reactive voltage partition and an active network loss voltage partition is adopted. And defining a set domain at the intersection of the two sub-regions. And voltage regulation is carried out by utilizing reactive power regulation equipment in the aggregation domain, so that the voltage requirement can be met, and the requirement of minimizing the active network loss can also be met. The step of set domain partitioning is shown in figure 1. In fig. 1, reactive-voltage sensitivity weight divisions are shown by solid lines and active-network loss-voltage sensitivity weight divisions are shown by dashed lines.
Due to the characteristic of weak coupling between each set domain, when the set domain where the out-of-limit node is located is adjusted, the adjacent set domains are slightly affected correspondingly. Therefore, in each subarea, the reactive compensation devices with different sensitivities participate in voltage regulation in turn according to the reactive compensation capability, so that the loss caused by frequent action of the reactive compensation devices can be reduced, and the voltage fluctuation can be regulated to a reasonable range by using the minimum reactive power. This is more efficient than adopting a traditional centralized control of the reactive power compensation device.
The minimum reactive adjustment amount in the aggregate domain to meet the out-of-limit voltage standard can be expressed as:
Figure BDA0003401563890000091
wherein, U in the formulaimax、UiminRespectively, the upper and lower limits of the node voltage. U shapeiIs the i node voltage, Si,iIs the self reactive-voltage sensitivity at the i-node. The specific flow chart is shown in figure 2. Firstly, whether the node voltage is out of limit or not is determined, if the node voltage is out of limit, the node voltage is subjected to threshold adjustment on the basis of the modularity function model provided aboveAnd partitioning the reactive power-voltage sensitivity weight and the active power network loss-voltage sensitivity weight of the line. And dividing a set domain, calculating reactive support capability in the set domain, if the reactive support capability in the set domain is more than 15%, selecting a reactive compensation device in the set domain to perform reactive compensation, otherwise, firstly meeting reactive requirements in reactive subareas.
Simulation analysis
In order to better explain the invention patent, a method adopting simulation analysis is further introduced. The stepwise analysis was performed in a modified IEEE33 node example. An exemplary wiring diagram is shown in FIG. 3. The example includes 33 nodes of the generator, wherein reactive compensation devices are arranged at the nodes 9, 15, 17, 20, 23 and 29.
The reactive compensation capacity of the compensation node is shown in the following table 1
Figure BDA0003401563890000092
The examples perform reactive-voltage sensitivity weight partitioning and active grid loss-voltage sensitivity weight partitioning. Since the node 1 is a balance node and does not participate in the partitioning step, the calculation example is partitioned according to the two sensitivity weight partitioning methods provided by the invention, and the results are respectively shown in fig. 4 and 5. Fig. 4 shows the reactive-voltage sensitivity weight partition results, which are 5 partitions in total. Fig. 5 shows the result of the division of the active network loss-voltage sensitivity weight, which has 4 divisions.
According to the partition result, the partition of the IEEE33 node sample set domain is shown in figure 6. There are 7 aggregation domains in total in fig. 6. The indexes of the reactive support capability in each aggregation domain are shown in the table 2. The calculation example is divided into 7 set domain partitions, wherein the reactive support capacity K is 0 in the set domain 3 and the set domain 5. If there are voltage limit points in the aggregation domains 3 and 5, firstly, in order to meet reactive power requirements, the reactive power-voltage sensitivity partitions are used for adjustment, the aggregation domain 3 is divided into reactive power partitions composed of nodes 4, 5, 6, 7, 8 and 9 for adjustment, and the aggregation domain 5 is divided into reactive power partitions composed of nodes 10, 11, 12, 13, 14, 15, 16, 17 and 18 for adjustment, without considering the active network loss-voltage sensitivity partitions.
TABLE 2 improved IEEE33 node algorithm aggregation domain partitioning and reactive support capability within an aggregation domain
Figure BDA0003401563890000101
The voltage adjustment is performed for the first voltage over-limit point 7 in the example. The compensation results of each node are shown in Table 3
TABLE 3 node-to-node 7 node Compensation
Figure BDA0003401563890000102
As can be seen from table 3, the node 9 in the same domain partition has the best regulation capability for the voltage threshold 7. The reactive power compensation device at node 9 has the largest voltage rise and less active network loss.
By adopting the control strategy of the invention, after the voltage limit points are subjected to the partitioned reactive compensation, the voltage of each node is as shown in figure 7. Fig. 7 also shows the difference between the voltages at the nodes before and after adjustment.
It can be seen from fig. 7 that the voltage of each node can be improved by the partition control of the present invention. The nodes 19 and 20 are arranged at the head end of the line, no node voltage in the set domain partitions exceeds the limit, and the voltages of the nodes 19 and 20 are unchanged according to the characteristic of weak coupling between the set domain partitions, so that the requirement of the partitions is met.
In order to illustrate the economical efficiency of the control method provided by the invention, a method for centralized control of the calculation examples without partitioning is adopted, and the two control methods are compared.
In the method of non-partitioned centralized control, all reactive compensation devices in the example participate in voltage regulation, all nodes are considered to be in one partition, and the voltage of 7 nodes in the two control methods is compared with the active network loss, and the result is shown in table 4.
TABLE 4 comparison of results of two control methods
Figure BDA0003401563890000111
As can be seen from table 4, in the partition control manner, compared with the centralized control manner, the voltage at the 7-node is improved by 0.01p.u., the power network loss is reduced by 0.044MW, and the partition control manner is relatively better. The voltage overlimit point in the zone is only optimized and adjusted in a zone control mode, and the zone control method has pertinence. And the centralized control mode is to carry out optimization control on all the reactive power adjusting devices, and belongs to global optimization control.

Claims (1)

1. A voltage coordination control method based on a reactive power-active power network loss partition set domain is characterized by comprising the following steps: the method comprises the following steps:
s1, calculation of reactive power-voltage and active network loss-voltage sensitivity
Assuming that the total number of nodes is N, including the reactive node set { G } and the load nodes { L } that can provide reactive power, the system includes the control model of the above nodes as follows:
Figure FDA0003401563880000011
wherein H, N, J, L are the elements in the control matrix, respectively, Δ QGFor reactive node reactive power variation, Δ QLFor load node reactive power variation, Δ UGFor the magnitude change of the voltage of the reactive node, Δ ULIs the voltage variation of the load node;
if the node is both a reactive node and a load node, the formula (1) is:
[ΔQG]＝[HGG LLL][ΔUL] (2)
assuming the injected reactive power at the load node is unchanged, i.e.: delta QLEliminating the reactive node voltage variation Δ U by equation (1) when it is 0GAnd obtaining a sensitivity expression between the unit voltage amplitude of the load i node and the reactive variable quantity of the reactive j node as follows:
Figure FDA0003401563880000012
the node voltage amplitude variation is expressed as:
ΔU＝SQU,ijΔQ (4)
in a network with the number of nodes being N, the system active network loss-voltage relationship is expressed as follows:
Figure FDA0003401563880000013
the sensitivity of the whole network active network loss to reactive power is represented by using differential, and the sensitivity is rewritten into a matrix form:
Figure FDA0003401563880000014
the sensitivity expression of the system network loss to the node power change is as follows:
Figure FDA0003401563880000015
since the reactive power change directly affects the voltage change, equations (8) to (9) are satisfied:
Figure FDA0003401563880000016
Figure FDA0003401563880000017
the active network loss-voltage sensitivity expression obtained according to the formulas (7) and (9) is as follows:
Figure FDA0003401563880000021
s2 sensitivity-based weighting
And weighting the reactive-voltage sensitivity to obtain:
w＝SQU,ij·Qi,j (11)
wherein:
Figure FDA0003401563880000022
in the formula: sQU,ijIs the reactive-voltage sensitivity between the i node and the j node; qi,j,1Representing reactive power, Q, of the input line from the head endi,j,2Indicating reactive power, S, of the end outgoing lineQU,ijThe smaller the voltage influence of the reactive node on the load node, Qi,jThe smaller the reactive power transmitted between the node i and the node j is, the same weight is given to the node i and the node j;
using an electrical matrix of impedances, element d of the matrixijExpressed as:
dij＝zii+zjj-zij-zji (13)
the electrical distance matrix is obtained by simplifying the node impedance matrix:
Figure FDA0003401563880000023
the active network loss-voltage sensitivity weight expression is:
wij＝SPlossU,ij·dij (15)
in the formula, SijFor active network loss-voltage sensitivity, dijIs the electrical distance between node i and node j, which is an element in the electrical distance matrix, SijSmaller represents a smaller link between the active network loss and the line ij, dijThe smaller the electrical distance between the node i and the node j is, the same weight is given to the node i and the node j;
s3, establishing a modularity function model
The modularity function formula is defined as follows:
Figure FDA0003401563880000024
wherein: a. theijIs a connecting line between the node i and the node j, if the node i is connected with the node j, Aij1, otherwise Aij0, according to AijThe characteristic of (A) is that the connection matrix without phase diagram is a symmetrical matrix along the main diagonal, namely Aij＝AjiIf the node i and the node j are in the same partition, the delta function is 1, otherwise, delta (i, j) is 0;
Figure FDA0003401563880000025
m represents the sum of all weights in the network:
Figure FDA0003401563880000031
and improving the modularity function, wherein the improved modularity function is as follows:
Figure FDA0003401563880000032
wherein A isijIs a weight sensitivity value, i.e. Aij＝wijThen k isiRepresents the sum of all weights connected to node i, i.e.:
Figure FDA0003401563880000033
calculating a modularity function by using the weight indexes, representing the weight coupling degrees among different nodes, and partitioning the nodes with different coupling degrees;
s4, establishing reactive support capability index
The reactive support capability index is expressed as:
Figure FDA0003401563880000034
wherein QiFor the total reactive power compensation capacity in a zone, i.e. the sum of the maximum reactive output capacities of all reactive power compensation devices in a zone, QqConsidering maximum load and power flow in the subarea, considering that the subarea has enough reactive power when K is more than or equal to 15-20%, the subarea is suitable, when K is more than or equal to 15-20%<When the percentage of the total power is 15%, the reactive power in the subareas is considered to be insufficient;
s5, for the power system network containing N nodes, the partitioning step by using the improved modularity function model is as follows:
(1) initializing each node of the power system, and calculating an improved modularity function by taking each node as an independent sub-partition;
(2) for the node i, randomly selecting a node j from the nodes connected with the node i to calculate improved modularity, selecting a new partition with the largest calculated value, and updating the improved modularity;
(3) repeating the step 2 for the new partition until all nodes in the power system are traversed;
(4) stopping partitioning when no new partition is divided or the improved modularity calculation value reaches the maximum;
(5) respectively marking out a reactive power-voltage sensitivity subarea and an active power network loss-voltage sensitivity subarea by the steps;
s6 partition voltage control strategy
The minimum reactive power adjustment quantity meeting the out-of-limit voltage standard in the set domain is represented as:
Figure FDA0003401563880000035
whereinIn the formula of Ui max、Ui minUpper and lower limits of the node voltage, U, respectivelyiIs the i node voltage, Si,iIs the self reactive-voltage sensitivity at the i-node.
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