CN-121980116-A - Distributed photovoltaic grid-connected limit capacity calculation method, system, equipment and medium

CN121980116ACN 121980116 ACN121980116 ACN 121980116ACN-121980116-A

Abstract

The invention relates to the technical field of photovoltaic grid-connected capacity calculation, and discloses a method, a system, equipment and a medium for calculating the limit capacity of distributed photovoltaic grid-connected, wherein the method comprises the steps of establishing a limit capacity optimization model according to the operation parameters and the topological structure of a power distribution network; the method comprises the steps of obtaining a limit capacity optimization model, solving the limit capacity optimization model to obtain initial limit photovoltaic access capacity of a power distribution network and a power distribution network running state, carrying out key constraint node identification on access nodes distributed with the initial limit photovoltaic access capacity according to the power distribution network running state to obtain key constraint nodes, setting self-adaptive capacity constraint of the key constraint nodes, carrying out iterative solution on the limit capacity optimization model according to the self-adaptive capacity constraint until an iterative stopping condition is reached, and obtaining a final limit photovoltaic access capacity and node capacity distribution result. According to the invention, through a node sensitivity self-adaptive regulation mechanism, on the premise of ensuring operation safety and controllable uncertainty risk, the overall photovoltaic acceptance of the power distribution network is remarkably improved.

Inventors

ZHANG MANYING
LIN LING
Liu Daikai
HUANG JINGJING
DAI PAN
HU ZHECHENG
LI FAN
ZHU CHAO
ZHANG MENGQI
XUE YOU
CHEN XILIN

Assignees

国网浙江省电力有限公司经济技术研究院

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (10)

1. The method for calculating the limit capacity of the distributed photovoltaic grid connection is characterized by comprising the following steps of: According to the operation parameters and the topological structure of the power distribution network, maximizing the access capacity of the distributed photovoltaic access power distribution network as an objective function, and establishing a limit capacity optimization model by taking system power flow constraint, power balance constraint and photovoltaic output and installation upper limit constraint as constraint conditions; Solving the limit capacity optimization model to obtain the initial limit photovoltaic access capacity of the power distribution network and the corresponding power distribution network running state; According to the running state of the power distribution network, performing key constraint node identification on access nodes allocated with initial limit photovoltaic access capacity to obtain key constraint nodes, and setting self-adaptive capacity constraint of the key constraint nodes; And carrying out iterative solution on the limit capacity optimization model according to the self-adaptive capacity constraint until a preset iterative stop condition is reached, so as to obtain a final limit photovoltaic access capacity and node capacity allocation result.
2. The method for calculating the limit capacity of the distributed photovoltaic grid-connected system according to claim 1, wherein the step of solving the limit capacity optimization model to obtain the initial limit photovoltaic access capacity of the power distribution network and the corresponding operation state of the power distribution network comprises the following steps: Converting the limit capacity optimization model into a mixed integer second order cone planning model by adopting second order cone relaxation treatment, and carrying out opportunity constraint on node voltage and branch current to construct node voltage opportunity constraint and branch current opportunity constraint; And solving the mixed integer second order cone planning model to obtain the initial limit photovoltaic access capacity of the power distribution network and the corresponding power distribution network running state.
3. The method for calculating the limit capacity of the distributed photovoltaic grid-connected system according to claim 2, wherein the step of identifying the key constraint node for the access node allocated with the initial limit photovoltaic access capacity according to the operation state of the power distribution network, and obtaining the key constraint node comprises the following steps: according to the running state of the power distribution network, performing index calculation on access nodes allocated with initial limit photovoltaic access capacity to obtain node sensitivity of the access nodes, and performing activation degree calculation on running constraint of the power distribution network to obtain constraint activation degree of the power distribution network nodes; And calculating key constraint scores of the access nodes according to the node sensitivity and the constraint activation degree, and selecting a plurality of key constraint nodes from the access nodes according to the key constraint scores.
4. The method for calculating the limit capacity of the distributed photovoltaic grid-connected system according to claim 3, wherein the step of calculating the node sensitivity of the access node and the activation degree of the operation constraint of the power distribution network according to the operation state of the power distribution network to obtain the constraint activation degree of the power distribution network node comprises the following steps: Calculating the node voltage sensitivity of the access node according to the installed capacity of the access node and the node voltages of other power distribution network nodes; calculating the node current sensitivity of the access node according to the installed capacity of the access node and the branch current of other power distribution network nodes; Calculating the voltage constraint activation degree of the power distribution network nodes according to the node voltage and the node voltage upper limit value of each power distribution network node; and calculating the current constraint activation activity of the power distribution network nodes according to the branch current and the branch current upper limit value of each power distribution network node.
5. The method according to claim 4, wherein the step of calculating key constraint scores of the access nodes according to the node sensitivities and the constraint activities, and selecting a plurality of key constraint nodes from the access nodes according to the key constraint scores comprises: taking the product of the node voltage sensitivity of the access node and the voltage constraint activation degree of the corresponding power distribution network node as the voltage constraint score of the access node; taking the product of the node current sensitivity of the access node and the current constraint activation degree of the corresponding power distribution network node as the current constraint score of the access node; and taking the sum of the maximum values of the voltage constraint scores and the current constraint scores as key constraint scores of the access nodes, and selecting a preset number of nodes from the access nodes as key constraint nodes according to descending order of the key constraint scores.
6. The method of claim 3, wherein the step of setting the adaptive capacity constraint of the critical constraint node comprises: Updating the upper limit of the allowed access capacity according to the upper limit of the allowed access capacity of the key constraint node and the key constraint score; And constructing the self-adaptive capacity constraint of the key constraint node according to the updated allowable access capacity upper limit.
7. The method for calculating the limit capacity of the distributed photovoltaic grid-connected system according to claim 4, wherein the step of iteratively solving the limit capacity optimization model according to the adaptive capacity constraint until a preset iteration stop condition is reached, and obtaining a final limit photovoltaic access capacity and node capacity allocation result comprises: Updating the node voltage margin in the node voltage opportunity constraint according to the difference between the voltage constraint activation degree and a preset first activation degree threshold value to obtain an updated node voltage opportunity constraint; Updating the branch current margin in the branch current opportunity constraint according to the difference between the current constraint activation degree and a preset second activation degree threshold value to obtain an updated branch current opportunity constraint; And carrying out iterative solution on the mixed integer second-order cone planning model according to the updated node voltage opportunity constraint, the updated tributary current opportunity constraint and the self-adaptive capacity constraint until a preset iterative stopping condition is reached, so as to obtain a final limit photovoltaic access capacity and node capacity allocation result.
8. A distributed photovoltaic grid-tied limit capacity computing system, comprising: the initial capacity calculation module is used for establishing a limit capacity optimization model by taking the maximum access capacity of the distributed photovoltaic access power distribution network as an objective function and taking system power flow constraint, power balance constraint and photovoltaic output and installation upper limit constraint as constraint conditions according to the operation parameters and the topological structure of the power distribution network; Solving the limit capacity optimization model to obtain the initial limit photovoltaic access capacity of the power distribution network and the corresponding power distribution network running state; The key constraint identification module is used for carrying out key constraint node identification on the access nodes distributed with the initial limit photovoltaic access capacity according to the running state of the power distribution network to obtain key constraint nodes, and setting the self-adaptive capacity constraint of the key constraint nodes; And the final capacity calculation module is used for carrying out iterative solution on the limit capacity optimization model according to the self-adaptive capacity constraint until a preset iterative stop condition is reached, so as to obtain a final limit photovoltaic access capacity and node capacity allocation result.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any one of claims 1 to 7 when the computer program is executed by the processor.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 7.

Description

Distributed photovoltaic grid-connected limit capacity calculation method, system, equipment and medium Technical Field The invention relates to the technical field of photovoltaic grid-connected capacity calculation, in particular to a distributed photovoltaic grid-connected limit capacity calculation method, a system, equipment and a medium. Background Along with the continuous increase of the capacity of the distributed photovoltaic installation, the power distribution network gradually evolves from a traditional unidirectional power supply structure to a source-load bidirectional interaction structure, and higher requirements are provided for power grid planning, operation and safety evaluation. In the prior art, for the access capability evaluation of large-scale distributed photovoltaic in a power distribution network, a method based on deterministic power flow calculation is generally adopted, or the photovoltaic grid-connected capacity is statically analyzed by combining with an empirical configuration rule. The method takes constraints such as node voltage, branch current, transformer capacity and the like as criteria, and judges whether a system touches an operation boundary or not by gradually increasing the installed scale of the photovoltaic, so that the maximum accessible capacity of the distributed photovoltaic is determined. However, in the context of high permeability photovoltaic access, the above-described prior art increasingly exposes a series of drawbacks and deficiencies that are difficult to ignore. First, under high permeability operating conditions, there is a significant difference in the sensitivity of different access nodes to changes in photovoltaic output. The influence of the photovoltaic access on node voltage lifting, branch current change and transformer power flow direction is not balanced among different nodes under the influence of the topological structure of the power distribution network, line impedance distribution, load space distribution and other factors. The existing assessment method generally adopts a unified or static photovoltaic access upper limit setting mode, and cannot effectively describe the sensitivity difference of each node to the system operation constraint, so that non-key nodes are easy to trigger voltage or current constraint in advance, the overall photovoltaic acceptance capacity of the system is limited, and the waste of potential accessible capacity is caused. Secondly, in the operation period of higher photovoltaic output and lower load level, the problem of reverse tide is easily caused by large-scale distributed photovoltaic access. The reverse power flow not only can obviously raise the voltage of the end node of the feeder line and frequently trigger the voltage out-of-limit risk, but also can cause the phenomenon of unexpected power dumping of the transformer and the upper power grid to influence the safe operation of equipment. The reverse power flow flows in the distribution line to introduce extra loss, so that the phenomenon that the total network loss of the system does not drop and rise under the condition of high photovoltaic permeability is deviated from the original purpose of reducing the system loss of the distributed photovoltaic. The prior art relies on empirical configuration strategies or post-verification modes to avoid the problems, and lacks an active adjustment mechanism based on the operation characteristics of the system. Again, from the perspective of model construction and calculation methods, conventional distributed photovoltaic access capacity assessment methods have significant shortcomings in dealing with non-linear operating characteristics of the power distribution network. On one hand, the complexity of the model is reduced by partial methods through linear approximation or simplified constraint, the nonlinear coupling relation among voltage, current and tide under the condition of high permeability is difficult to accurately reflect, and the evaluation result is easy to be conservative or distorted. On the other hand, with the increase of the number of photovoltaic access nodes and analysis scenes, the model scale is rapidly enlarged, the calculation complexity is remarkably improved, the existing method is difficult to consider solving efficiency while guaranteeing the precision, and the application of the method in large-scale power distribution network engineering practice is limited. Finally, most of the existing limit capacity calculation focuses on 'calculating limit capacity results per se', and deep description of limit capacity influence mechanisms is lacking, especially in the process that limit capacity gradually approaches to a system operation boundary, key nodes which play a leading role in constraint triggering cannot be dynamically identified, and photovoltaic access strategies of all nodes are adjusted accordingly, so that the capacity assessment process lacks pertinence and self-adaptiv