CN-121984025-A - Distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering distribution network operation safety constraint

CN121984025ACN 121984025 ACN121984025 ACN 121984025ACN-121984025-A

Abstract

The invention discloses a distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraint, which comprises the steps of firstly modeling probability distribution of distributed photovoltaic power generation power by adopting a multi-element Gaussian mixture model to describe non-Gaussian characteristics and spatial correlation of a plurality of distributed photovoltaic power output, secondly constructing a second-order cone planning model by taking the power flow constraint of a distribution network circuit, the node voltage safety constraint and the inverter capacity constraint into consideration with the maximization of the upward and downward power adjustment range of the distributed photovoltaic polymerization as a target, and finally providing a multi-element Gaussian mixture point estimation algorithm, and obtaining probability distribution of the distributed photovoltaic polymerization frequency modulation reserve capacity by constructing a special sampling set and executing a small amount of deterministic calculation and combining statistical analysis and weighted mixture. The method effectively analyzes the frequency modulation capability of the large-scale distributed photovoltaic polymerization and quantifies the uncertainty of the frequency modulation capability, and combines the calculation precision and the calculation efficiency.

Inventors

SHEN ZHONGKAI
HE ZHIQIANG
SONG YI
Wan can
Qin Hongpei
LIU HUI
WANG YUPENG
ZHAO BO
CHEN XIAOGANG
SUN KE
Xiao Rongcan

Assignees

浙江大学

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (9)

1. A distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering distribution network operation safety constraint is characterized by comprising the following steps: 1) Modeling and characterizing the joint probability distribution of a plurality of distributed photovoltaic power generation powers in the power distribution network by adopting a multi-element Gaussian mixture model to obtain a joint probability density function; 2) Constructing an objective function by maximizing upward and downward power adjustment quantity of distributed photovoltaic aggregation, taking power flow constraint of a power distribution network, safe operation constraint of the power distribution network and capacity constraint of a distributed photovoltaic inverter as constraint conditions, and constructing a distributed photovoltaic aggregation frequency modulation capacity assessment model by combining second order cone planning; 3) Combining the basic principles of the decorrelation transformation and the point estimation method, generating a plurality of distributed photovoltaic power generation power sample points corresponding to all Gaussian components in the multi-element Gaussian mixture model, and further constructing a distributed photovoltaic power generation power sample set; 4) Substituting each generated sample into a distributed photovoltaic polymerization frequency modulation capability evaluation model to perform deterministic calculation, so as to obtain a distributed photovoltaic polymerization frequency modulation capability sample set; 5) Based on the distributed photovoltaic polymerization frequency modulation capability sample set, statistical moments of the distributed photovoltaic polymerization frequency modulation capability samples are counted, and weighted mixing is carried out according to weights of all Gaussian components, so that the distributed photovoltaic polymerization frequency modulation capability probability distribution in a Gaussian mixed mode is obtained.
2. The distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering the operation safety constraint of the distribution network according to claim 1 is characterized in that in the step 1), the joint probability density function is obtained by weighting and superposing a plurality of Gaussian components, each Gaussian component has a corresponding weight coefficient, the sum of all the weight coefficients is 1 and is non-negative, each Gaussian component is described by a mean value vector and a covariance matrix, and the whole is used for precisely fitting joint probability distribution of a plurality of distributed photovoltaic output powers, so that non-Gaussian characteristics and spatial correlation of the joint probability density function are fully reflected.
3. The distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraints according to claim 1 is characterized in that in step 2), an objective function is to maximize the sum of an upward power adjustment amount of distributed photovoltaic polymerization, a downward power adjustment amount of polymerization and active power loss of all branches of a distribution network, wherein the upward power adjustment amount of polymerization is obtained based on the upward power adjustment amount of each distributed photovoltaic and a corresponding linearization constant, and the downward power adjustment amount of polymerization is obtained based on the downward power adjustment amount of distributed photovoltaic and the corresponding linearization constant.
4. The distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraint according to claim 3, wherein in step 2), the constraint condition specifically comprises: The power flow constraint of the distribution network is that a DistFlow model relaxed by a second order cone is adopted to describe and determine the association relationship between active power and reactive power of a branch and node voltage and current; The safe operation constraint of the power distribution network is that the square of the current amplitude of a branch does not exceed the square of the maximum current allowed to flow through the branch, and the square of the node voltage amplitude is required to be maintained between the set node voltage safety upper limit square and the set node voltage safety lower limit square; The capacity constraint of the distributed photovoltaic inverter is that the active power of the distributed photovoltaic output is equal to the maximum available active power minus the upward power adjustment amount, the active power of the distributed photovoltaic output is not smaller than the downward power adjustment amount, the combination of the active power and the reactive power is required to meet the nominal capacity constraint of the inverter, the upward power adjustment amount ranges from 0 to the product of the maximum allowable upward standby proportional coefficient and the nominal capacity of the inverter, and the downward power adjustment amount ranges from 0 to the product of the maximum allowable downward standby proportional coefficient and the nominal capacity of the inverter.
5. The distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraint according to claim 1 is characterized in that in the step 3), the distributed photovoltaic power generation power sample set is obtained through the steps of firstly processing original related distributed photovoltaic power generation power vectors by using a Cholesky decomposition technology for each Gaussian component in a multi-element Gaussian mixture model to obtain mutually independent distributed photovoltaic power generation power vectors, then combining a two-point estimation method principle to sample in a mutually independent distributed photovoltaic power generation power vector space after transformation, determining specific sampling values according to the mean value, standard deviation, third-order central moment and distributed photovoltaic number of the corresponding Gaussian components, and finally restoring the independent sampling points to an original space through inversion conversion to form a distributed photovoltaic power generation power sample with the correlation, thereby constructing the distributed photovoltaic power generation power sample set.
6. The distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraint according to claim 5, wherein in step 4), each generated sample is substituted into a distributed photovoltaic polymerization frequency modulation capability assessment model to perform deterministic calculation, and a distributed photovoltaic polymerization frequency modulation capability sample set is obtained, and the specific process is as follows: And (3) regarding each power sample vector in the sample set as a deterministic scene of the maximum available power of the distributed photovoltaic at a certain moment, substituting the deterministic scene into the evaluation model constructed in the step (2) one by one, obtaining a corresponding sample value of the distributed photovoltaic polymerization frequency-up capability and a sample value of the polymerization frequency-down capability under each scene through solving, and jointly forming a sample set of the distributed photovoltaic polymerization frequency-up capability by the sample values of all the scenes to provide data support for subsequent probability evaluation.
7. The method for evaluating the probability of the distributed photovoltaic polymerization frequency modulation capability taking the operation security constraint of the distribution network into consideration according to claim 6, wherein in step 5), the statistical moment of the distributed photovoltaic polymerization frequency modulation capability sample is counted based on the distributed photovoltaic polymerization frequency modulation capability sample set, and weighted mixing is performed according to the weight of each gaussian component, so as to obtain the probability distribution of the distributed photovoltaic polymerization frequency modulation capability in a gaussian mixed form, which specifically comprises: Firstly, based on the aggregate upward and downward frequency modulation capability sample values obtained in the step 4), respectively calculating the average value and standard deviation of the aggregate upward frequency modulation capability and the aggregate downward frequency modulation capability under each Gaussian component by combining the weight coefficients corresponding to the samples, and then, according to the weight of each Gaussian component, carrying out weighted mixing on the average value and standard deviation corresponding to all Gaussian components, and finally, constructing the distributed photovoltaic aggregate upward frequency modulation capability probability distribution and the aggregate downward frequency modulation capability probability distribution in a Gaussian mixed mode.
8. A computer readable storage medium having stored thereon computer instructions for causing a computer to perform the steps of the method according to any of claims 1-7.
9. An electronic device, comprising: One or more processors; A memory for storing one or more programs; The one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of any of claims 1-7.

Description

Distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering distribution network operation safety constraint Technical Field The invention relates to a distributed photovoltaic polymerization frequency modulation capability probability assessment method considering distribution network operation safety constraint, and belongs to the field of uncertainty analysis of power systems. Background With the large-scale access of distributed photovoltaics, the comprehensive inertia of the whole power system is rapidly shrinking, and the frequency regulation capability is continuously reduced. The large number of distributed photovoltaics integrated in a power distribution network has the potential to actively participate in the frequency regulation of the power system. The aggregation frequency supporting capability of the distributed photovoltaic in the power distribution network is fully excavated and utilized, and the method has important significance for improving the operation safety of a new energy power system. However, unlike conventional synchronous generator sets, distributed photovoltaic has extremely high randomness in that its power generation and available frequency modulation capability are affected by external factors such as solar irradiance, ambient temperature, and system operating conditions. Thus, distributed photovoltaics face a strong uncertainty challenge in providing frequency support services to the grid. In addition, large-scale distributed photovoltaic access causes the safety risks of the distribution network such as line power countercurrent, node voltage out-of-limit and the like. And according to the related grid-connected standard, the reactive output of the inverter needs to be regulated by the distributed photovoltaic to participate in the regulation and control of the distribution network voltage. Therefore, when the distributed photovoltaic supports the system frequency, the local operation safety of the distribution network is considered. Because the power transmission system operators are difficult to directly perceive the distributed photovoltaic polymerization frequency modulation capability of mass dispersion, and the existing certainty evaluation method cannot process the randomness of the photovoltaic output, the excavation of the distributed photovoltaic polymerization frequency modulation potential is insufficient. While the traditional point estimation method generally assumes that the input random variable is subjected to Gaussian distribution, the non-Gaussian characteristic and the complex space-time correlation of the distributed photovoltaic output cannot be processed, and the probability estimation result is inaccurate. Therefore, there is a need for an accurate and efficient evaluation method to fully consider the uncertainty of the distributed photovoltaic power generation power and the safe operation requirement of the distribution system, and to mine and evaluate the frequency modulation capability of the large-scale distributed photovoltaic aggregation. Disclosure of Invention Aiming at the limitations of the related background technology, the invention provides a distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering the operation safety constraint of a distribution network. Firstly, describing probability distribution of distributed photovoltaic power generation by adopting a multi-Gaussian mixture model, accurately representing non-Gaussian characteristics and multi-correlation of the distributed photovoltaic power generation, secondly, constructing a distributed photovoltaic polymerization frequency modulation capacity assessment model considering network-level power flow, voltage safety constraint and equipment-level inverter capacity constraint so as to mine large-scale distributed photovoltaic polymerization frequency modulation capacity, and finally, fusing the Gaussian mixture model and a point estimation algorithm, and obtaining the probability distribution of the distributed photovoltaic polymerization frequency modulation capacity through a small amount of deterministic calculation and statistical analysis. In order to achieve the above purpose, the present invention adopts the following technical scheme: a distributed photovoltaic polymerization frequency modulation capability probability evaluation method considering distribution network operation safety constraint comprises the following steps: 1) Modeling and characterizing the joint probability distribution of a plurality of distributed photovoltaic power generation powers in the power distribution network by adopting a multi-element Gaussian mixture model to obtain a joint probability density function; 2) Constructing an objective function by maximizing upward and downward power adjustment quantity of distributed photovoltaic aggregation, taking power flow constraint of a power di