CN-122026392-A - Photovoltaic field station frequency supporting capability online evaluation method and system

CN122026392ACN 122026392 ACN122026392 ACN 122026392ACN-122026392-A

Abstract

The invention provides a photovoltaic station frequency supporting capacity online evaluation method and a system, wherein the method comprises the steps of constructing a Coulomb dictionary function according to a topological structure of a target power grid in a photovoltaic station and related parameters of the photovoltaic station; the method comprises the steps of obtaining historical operation data of a photovoltaic station under multiple working conditions, calling a Coulomb dictionary function to process the historical operation data to obtain a high-dimensional time sequence data set, determining a Coulomb operator representing a linear evolution rule of a photovoltaic system in the photovoltaic station based on the high-dimensional time sequence data set, constructing linear programming equation constraint based on the Coulomb operator, constructing inequality constraint based on safe operation conditions of the photovoltaic station, constructing a linear programming model by combining the equation constraint, the inequality constraint and a pre-constructed objective function, inputting the current operation data of the photovoltaic station into the linear programming model, and solving to obtain multi-dimensional quantitative evaluation information.

Inventors

ZHANG XIPENG
LIU ZHONG
CHEN XINYI
ZHOU YINGYING
LI TAO

Assignees

国家电网有限公司华东分部

Dates

Publication Date: 20260512
Application Date: 20251204

Claims (10)

1. An on-line evaluation method for frequency support capability of a photovoltaic field station is characterized by comprising the following steps: Constructing a Coulomb dictionary function according to the topological structure of a target power grid in a photovoltaic station and related parameters of the photovoltaic station, wherein the related parameters of the photovoltaic station are related to illumination, temperature and photovoltaic station components; acquiring historical operation data of the photovoltaic station under multiple working conditions, and calling the Coulomb dictionary function to process the historical operation data to obtain a high-dimensional time sequence data set; determining a Coulomb operator for characterizing a linear evolution rule of a photovoltaic system in the photovoltaic field station based on the high-dimensional time sequence data set; constructing a linear programming equation constraint based on the Coulomb operator; Constructing an inequality constraint based on safe operating conditions of the photovoltaic field station; constructing a linear programming model by combining the equality constraint, the inequality constraint and a pre-constructed objective function, wherein the objective function is related to the single frequency modulation time scale standby power output quantity; And inputting the current operation data of the photovoltaic station into the linear programming model, and solving to obtain multi-dimensional quantitative evaluation information for evaluating the frequency supporting capacity of the photovoltaic station on line.
2. The method for online assessment of frequency support capability of a photovoltaic field station according to claim 1, wherein the photovoltaic field station related parameters comprise illumination intensity, temperature coefficient, component power characteristics and control strategies, and the control strategies comprise droop control and direct current capacitance inertia simulation; The kunman dictionary function includes: ; ; ; Wherein, the As an original part of the kulman dictionary function, As a modified part of the coulman dictionary function, The illumination intensity at the moment t is the illumination intensity at the moment t, The ambient temperature at the moment t is set to be, Is the direct-current capacitor voltage at the moment t, The power deviation of the photovoltaic output at the moment t, For the system frequency deviation at the time t, The output power of the converter is the time t, Is the sag factor at the moment t, For the system power disturbance at time t, The power of the photovoltaic MPPT point at the moment t, The superscript indicates the matrix transpose.
3. The method for online assessment of frequency support capability of a photovoltaic field station according to claim 1, wherein the determining a cupman operator characterizing a linear evolution law of a photovoltaic system in the photovoltaic field station based on the high-dimensional time series data set comprises: And processing the high-dimensional time sequence data set by adopting a least square method, and fitting to obtain a Coulomb operator representing the linear evolution rule of the photovoltaic system in the photovoltaic field station.
4. The photovoltaic field station frequency support capability online assessment method according to claim 1, wherein the constructing linear programming equation constraints based on the cuppman operator comprises: based on the initial value constraints and the evolution constraints of the variables of the Coulomb operator series; The variable initial constraint comprises Wherein The initial variable of the time sequence, The current operation parameters of the photovoltaic field station after the dimension rising conversion are obtained; the variable evolution constraint comprises , wherein, Is a Coulomb operator To the power of t, characterizes a linear relationship between the high-dimensional time series data at time t and the initial time data.
5. The method for online assessment of frequency support capability of a photovoltaic field station according to claim 1, wherein the constructing an inequality constraint based on safe operating conditions of the photovoltaic field station comprises: The following inequality constraint is constructed based on the safe operating conditions of the photovoltaic field station: ; Wherein, the For maximum output power of photovoltaic cells within the photovoltaic field station at the current illumination and temperature, For the maximum active capacity of the current transformer in the photovoltaic field station, Refers to the maximum fluctuation value of the DC capacitor voltage.
6. The method of on-line assessment of photovoltaic field station frequency support capability of claim 1, further comprising constructing the objective function comprising: constructing the objective function based on the extremum of the quantitative evaluation index of the single frequency modulation time scale standby power output quantity; The quantitative evaluation index includes: Potential value index including inertial time scale DC capacitance energy storage release potential Power average potential for single time scale standby ; The actual value index comprises the actual release amount of the direct-current capacitor energy storage Actual average value of single time scale standby power 。
7. The method of claim 6, wherein the potential value indicator further comprises a potential utilization indicator, the potential utilization indicator being a ratio between a potential value and a corresponding actual value, the potential value and the actual value comprising a potential value and an actual value of a capacitive energy storage release amount, and a potential value and an actual value of a single time scale standby power.
8. The method of on-line assessment of photovoltaic field station frequency support capability according to claim 1, wherein the constructing a linear programming model combining the equality constraint, the inequality constraint, and a pre-constructed objective function, the objective function being related to a single frequency modulation time scale standby power output, comprises: the objective function is expressed as: ; Constructing the linear programming model in combination with the equality constraint, the inequality constraint and the objective function; Wherein, the The actual energy storage of the direct current capacitor of the photovoltaic field station is released maximally, Refers to the capacitance value of the direct current capacitor, Refers to the initial voltage of the direct current capacitor, For a set dc capacitance minimum voltage, For maximum release of actual standby power for a wind farm, As the number of time sequences after the differential discrete, Is the capacity of the ith photovoltaic in the photovoltaic station.
9. The photovoltaic field station frequency support capability online assessment method according to claim 1, further comprising: Collecting current operation data through an SCADA system of a photovoltaic station and an EMS system of a target power grid, wherein the operation data at least comprises real-time illumination, temperature, direct-current voltage, power deviation and frequency deviation; And inputting the collected current operation data into the linear programming model.
10. An on-line evaluation system for frequency support capability of a photovoltaic field station, comprising: The first construction module is used for constructing a Coulomb dictionary function according to the topological structure of a target power grid in the photovoltaic field station and related parameters of the photovoltaic field station, wherein the related parameters of the photovoltaic field station are related to illumination, temperature and photovoltaic field station components; The processing module is used for obtaining historical operation data of the photovoltaic station under multiple working conditions, and calling the Coulomb dictionary function to process the historical operation data to obtain a high-dimensional time sequence data set; the determining module is used for determining a Coulomb operator for representing a linear evolution rule of a photovoltaic system in the photovoltaic field station based on the high-dimensional time sequence data set; the second construction module is used for constructing linear programming equation constraint based on the Coulomb operator; A third construction module for constructing an inequality constraint based on safe operating conditions of the photovoltaic field station; a fourth construction module, configured to construct a linear programming model by combining the equality constraint, the inequality constraint and a pre-constructed objective function, where the objective function is related to a single frequency modulation time scale standby power output; and the evaluation module is used for inputting the current operation data of the photovoltaic field station into the linear programming model, and solving to obtain multi-dimensional quantitative evaluation information for evaluating the frequency supporting capacity of the photovoltaic field station on line.

Description

Photovoltaic field station frequency supporting capability online evaluation method and system Technical Field The embodiment of the invention relates to the technical field of control of photovoltaic field stations of power systems, in particular to a method and a system for online evaluation of frequency supporting capability of a photovoltaic field station. Background Frequency safety is one of the important issues of safety and stability of power systems. The permeability of new energy represented by wind power is rapidly increased, the inertia characteristics of the power grid are changed, and complexity is injected into the problem of frequency stability. Meanwhile, in order to keep the frequency of the novel power system stable, new energy stations such as wind power plants and the like are required to have certain frequency supporting capability. However, since the frequency supporting capability of the wind farm is affected by wind resources and the own running state, etc., it is difficult to quantitatively evaluate. The permeability of photovoltaic as a new energy main power supply is continuously improved, the traditional synchronous generator is reduced in duty ratio, so that the inertia of a power grid is insufficient, the frequency adjustment capability is weakened, and the frequency safety becomes a core challenge of the stable operation of a novel power system. The photovoltaic field station needs to have frequency supporting capability, but the supporting capability is limited by illumination intensity, ambient temperature and equipment safety (the influence is remarkable, and accurate quantification needs to be realized through online evaluation). The existing photovoltaic frequency support evaluation method is concentrated on a model driving method, a data driving method and the like. The model driving method is generally based on a simplified mechanism model of a photovoltaic module, such as a single diode model, derives an evaluation index, but depends on a large number of module parameters, such as series resistance and photo-generated current, the deviation between actual parameters and theoretical values is large, the photovoltaic safety constraint direct current voltage and the capacity coupling of a converter are strong, a nonlinear programming problem is formed, the time for solving is usually 2s-3s, on-line requirements cannot be met, the data driving method mainly adopts neural network fitting historical data, but breaks away from photovoltaic physical mechanisms, such as the change rule of direct current capacitor energy storage characteristics and MPPT power along with illumination, the evaluation result is poor in interpretation, and extreme scenes, such as strong illumination and large disturbance data are scarce, so that the overall accuracy of the model is low, and a clear physical basis cannot be provided for engineering decision. In recent years, the evaluation method of the frequency supporting capability of the wind power plant is mainly divided into two types of model driving and data driving. The model driving method is mainly used for calculating an expression of a correlation coefficient or performing complex nonlinear programming calculation through a simplified wind power plant frequency support model, so that a frequency support capacity evaluation index is obtained. However, a large number of wind farm model parameters are needed by a similar method, a certain error exists between a result obtained by the existing parameter estimation method and the real parameters, part of mechanisms are simplified by the model, the evaluation speed is reduced by complex nonlinear calculation during evaluation, and the requirement of online evaluation is difficult to meet. The data driving method adopts a neural network and other fitting modes to carry out fitting calculation on the historical frequency modulation data to obtain a data fitting model, thereby rapidly calculating the defined evaluation index. However, the existing data driving method is separated from a mathematical model, the internal relation of the system is difficult to reflect, the interpretability of the evaluation result is to be questionable, and in the actual operation of the wind farm, the frequency modulation data in the limit scene is difficult to collect, so that the accuracy of the training result in the global range is difficult to ensure. From engineering application, the current technology lacks a quantitative evaluation system of a light Fu Duanshi capacitor energy storage and long-time power standby composite frequency modulation mode, so that the frequency modulation potential under different illumination and temperature working conditions is difficult to accurately identify, the frequency modulation power distribution and response strategy optimization of the photovoltaic station cannot be effectively guided, the photovoltaic frequency modulation resource is not fully utilized, and the frequ