CN-122026377-A - Photovoltaic grid-connected control method and system based on load clustering and virtual active power

CN122026377ACN 122026377 ACN122026377 ACN 122026377ACN-122026377-A

Abstract

The invention relates to a photovoltaic grid-connected control method and system based on load clustering and virtual active power, wherein the method comprises the following steps of obtaining historical load data of a distribution transformer, preprocessing, analyzing the load data through a clustering algorithm, and clustering and partitioning the load according to load characteristics; in each load partition, integrating real-time photovoltaic active power, load active power and load reactive power through virtual active power, and converting the load reactive power into active power, so that the reactive power sent by an inverter required by photovoltaic grid connection in a corresponding load partition is determined through the virtual active power, and photovoltaic grid connection control is performed. Compared with the prior art, the method effectively improves the stability of the photovoltaic access point through the reactive power of the inverter.

Inventors

JIANG BENJIAN
WANG YINCHAO
LIU XIN
HAN DONG
YU JUNXIA
GU WEN
SHEN JINGJING
LI YINONG

Assignees

国网上海市电力公司

Dates

Publication Date: 20260512
Application Date: 20251217

Claims (10)

1. The photovoltaic grid-connected control method based on load clustering and virtual active power is characterized by comprising the following steps of: Acquiring historical load data of the distribution transformer, preprocessing, analyzing the load data through a clustering algorithm, and clustering and partitioning the load according to load characteristics; in each load partition, integrating real-time photovoltaic active power, load active power and load reactive power through virtual active power, and converting the load reactive power into active power, so that the reactive power sent by an inverter required by photovoltaic grid connection in a corresponding load partition is determined through the virtual active power, and photovoltaic grid connection control is performed.
2. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 1, wherein the calculation expression of the virtual active power is: In the formula, Is the virtual active power of node j, The photovoltaic active power of the node j, n is the total number of the nodes, For a common path between the head node to node i and to node j, For a path between two adjacent nodes, And The resistance and reactance of the line respectively, Is the active power of the load of node j, Reactive power for the load of node j.
3. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 2, wherein the deriving process of the virtual active power comprises the following steps: determining the influence of active power change and reactive power change on the voltage amplitude according to the relation between the node voltage change and the node active and reactive increment; Dividing any node voltage into an uncontrollable increment and a controllable increment part, and determining the uncontrollable increment part of the power change of a single node j to the voltage of a single node i, so as to obtain the virtual active power change quantity of the node i to the node j; based on the virtual active power variation of the node i to the node j, and according to the limitation of the node voltage fluctuation, obtaining the photovoltaic reactive power variation of the node j; and applying the photovoltaic reactive power variable quantity of the node j to the influence of a single node on the whole network voltage to obtain the virtual active power.
4. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 3, wherein the expression of the relation between the node voltage variation and the node active and reactive increment is: the calculation expression of the influence of the active power change and the reactive power change on the voltage amplitude is as follows: In the formula, For the voltage magnitude increase at node i, To the effect of active power variations on voltage amplitude, For the effect of reactive power variation on the voltage amplitude, For the active power change delta of node j, For the delta reactive power change of node j, Is the rated voltage of the network; The expression of the single node j power change to the uncontrollable delta part of the single node i voltage is: In the formula, For an uncontrollable incremental portion of the voltage at node i, As the photovoltaic active delta of node j, For the active increment of the load of node j, Load reactive power increment of the node j; The expression of the virtual active power variation of the node i to the node j is as follows: the expression of the photovoltaic reactive power variation of the node j is as follows: In the formula, The photovoltaic reactive power variation of the node j.
5. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 4, wherein the expression of applying the photovoltaic reactive power variation of the node j to the influence of a single node on the whole network voltage is: In the formula, Is the photovoltaic active power of node j, Is the active power of the load of node j, Reactive power for the load of node j.
6. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 1, wherein the preprocessing process comprises: And obtaining a corresponding data graph by utilizing polynomial curve fitting or partial weighted regression fitting on the historical load data of the data missing so as to fill the missing data.
7. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 6, wherein in the preprocessing process, historical load data with the data missing proportion exceeding a preset threshold value is subjected to rejection processing.
8. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 1, wherein the clustering algorithm is a k-means algorithm.
9. The photovoltaic grid-connected control method based on load clustering and virtual active power according to claim 8, wherein the processing procedure of the k-means algorithm comprises: taking k data from a data set A to be clustered randomly, taking the k data as the first k clustering centers, setting the maximum iteration number as n, dividing the data set A into k classes, then obtaining the distance between each data and the clustering center, adding the distance into each class, and then solving the clustering center of each class again; The method comprises the steps of repeatedly dividing a data set A into k classes, then obtaining the distance between each data and a clustering center, adding the distance into each class, then solving the clustering centers of each class again until the k clustering centers are not changed, and obtaining a final clustering result.
10. A photovoltaic grid-connected control system based on load clustering and virtual active power, characterized by comprising a memory and a processor, the memory storing a computer program, the processor invoking the computer program to perform the steps of the method according to any of claims 1 to 9.

Description

Photovoltaic grid-connected control method and system based on load clustering and virtual active power Technical Field The invention relates to the technical field of photovoltaic grid-connected control, in particular to a photovoltaic grid-connected control method and system based on load clustering and virtual active power. Background Under the environment of a green electricity direct connection target, distributed photovoltaic power generation occupies a major part in industrial park power supply. Meanwhile, the operation environment of the industrial park under the distributed photovoltaic access is complex and changeable, and the fluctuation and randomness of the photovoltaic output influence the stable operation of the power distribution network. The clustering technology in the data mining is used for clustering the load curves of the power users, is one of the important means of load characteristic analysis, is commonly used for clustering algorithms based on division, clustering algorithms based on hierarchy, clustering algorithms based on density and based on models, and therefore has important significance in researching the photovoltaic grid-connected control based on load clustering partition. The method comprises the steps of providing a low-voltage distribution network multi-mode voltage control based on reactive power regulation of a photovoltaic inverter, providing a voltage sensitivity theory-based low-voltage distribution network multi-mode voltage control, defining a concept of virtual injection active power, realizing conversion between active power and reactive power of nodes, providing a daily load curve clustering analysis method based on a K-means++ algorithm, selecting an initial centroid by using a heuristic random seeding mode, measuring the clustering density and the clustering separation by using a clustering evaluation index based on an elbow rule, comprehensively evaluating and determining an optimal clustering number, avoiding the influence of the randomness of the initial centroid on clustering quality, and providing a dynamic equivalent modeling analysis of a distributed photovoltaic power generation system widely connected into the distribution network by the literature, wherein the dynamic equivalent method of the distribution network comprehensively considers the load and the dynamic characteristics of the photovoltaic power generation system based on a parameter identification method. The existing method is mainly characterized in that the influence of the load on the node is seldom considered by performing voltage control on the voltage offset of the measurement node, and the method faces large-scale distributed photovoltaic grid connection, has complex load characteristics, has no obvious load characteristics and has less application to the load characteristics. Disclosure of Invention The invention aims to overcome the defect that the influence of load on the node is rarely considered by performing voltage control on the voltage offset of a measurement node in the prior art, and provide a photovoltaic grid-connected control method and system based on load clustering and virtual active power. The aim of the invention can be achieved by the following technical scheme: a photovoltaic grid-connected control method based on load clustering and virtual active power comprises the following steps: Acquiring historical load data of the distribution transformer, preprocessing, analyzing the load data through a clustering algorithm, and clustering and partitioning the load according to load characteristics; in each load partition, integrating real-time photovoltaic active power, load active power and load reactive power through virtual active power, and converting the load reactive power into active power, so that the reactive power sent by an inverter required by photovoltaic grid connection in a corresponding load partition is determined through the virtual active power, and photovoltaic grid connection control is performed. Further, the calculation expression of the virtual active power is: In the formula, Is the virtual active power of node j,The photovoltaic active power of the node j, n is the total number of the nodes,For a common path between the head node to node i and to node j,For a path between two adjacent nodes,AndThe resistance and reactance of the line respectively,Is the active power of the load of node j,Reactive power for the load of node j. Further, the deriving process of the virtual active power includes: determining the influence of active power change and reactive power change on the voltage amplitude according to the relation between the node voltage change and the node active and reactive increment; Dividing any node voltage into an uncontrollable increment and a controllable increment part, and determining the uncontrollable increment part of the power change of a single node j to the voltage of a single node i, so as to obtain the virtual active p