CN-121984130-A - Distribution network low-voltage flexible interconnection control method for grid-structured converter

CN121984130ACN 121984130 ACN121984130 ACN 121984130ACN-121984130-A

Abstract

The invention relates to the field of flexible control of power distribution networks, in particular to a distribution network low-voltage flexible interconnection control method of a grid-structured converter, which solves the problems of insufficient prospective and precision of short-time nonlinear disturbance, delayed threshold trigger control response and weak disturbance identification capability of traditional distribution network control under the condition of high distributed energy permeation. The method comprises the steps of obtaining voltage and current instantaneous value sequences of multiple interconnection points of a power distribution network in real time, injecting the voltage and current instantaneous value sequences into a power flow field domain, constructing a self-adaptive grid topology deformed along with an operation state, generating a dynamic power streamline, monitoring a streamline curvature capturing mutation event, extracting waveform fragments and a grid deformation area to form a power disturbance characteristic package, driving a field deformation feedback power controller by the characteristic package, analyzing a distortion mode and grid stress distribution, and outputting a compensation deformation instruction. Therefore, accurate and self-adaptive flexible regulation and control of the power of the interconnection points of the power distribution network are realized. The method can improve the prospective sensing and cooperative inhibition capability of complex disturbance of the power grid.

Inventors

WANG XIAODONG
ZHENG LIJUN
TIAN XIAOLI
GENG PULONG
LEI ZHIPENG

Assignees

国网山西省电力有限公司长治供电分公司
太原理工大学

Dates

Publication Date: 20260505
Application Date: 20260403

Claims (10)

1. The distribution network low-voltage flexible interconnection control method of the grid-structured converter is characterized by comprising the following steps of: Acquiring real-time electrical waveforms of a plurality of interconnection points in a low-voltage power distribution network, wherein the real-time electrical waveforms comprise a voltage instantaneous value sequence and a current instantaneous value sequence; Injecting the real-time electrical waveform into a power flow field domain for dynamic analysis, constructing an adaptive grid topology which is deformed along with the change of the running state of the power distribution network in the power flow field domain, and generating a dynamic power streamline between nodes of the adaptive grid topology according to a voltage instantaneous value sequence and a current instantaneous value sequence; Tracking and capturing curvature abrupt change events of the dynamic power streamline, and when the local curvature of the dynamic power streamline exceeds a preset curvature threshold, extracting waveform fragments of the dynamic power streamline and an adaptive grid topological area to which the waveform fragments belong to form a power disturbance feature packet; The power disturbance feature packet is taken as input, a power controller based on field deformation feedback is driven, and the power controller based on the field deformation feedback outputs a field compensation deformation instruction according to the distortion mode of waveform fragments in the power disturbance feature packet and the stress distribution of the self-adaptive grid topological area; and based on the field compensation deformation instruction, the control of the low-voltage flexible interconnection of the distribution network is realized.
2. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-structured converter according to claim 1, wherein the step of injecting the real-time electrical waveform into a power flow field domain for dynamic analysis, and constructing an adaptive grid topology deformed with the change of the running state of the distribution network in the power flow field domain comprises the steps of: Calculating an active power instantaneous value and a reactive power instantaneous value at each sampling moment according to the voltage instantaneous value sequence and the current instantaneous value sequence; Constructing a two-dimensional power flow field domain by taking an active power instantaneous value as a horizontal axis coordinate and a reactive power instantaneous value as a vertical axis coordinate, and drawing a power state point at each sampling moment in the two-dimensional power flow field domain; connecting power state points of adjacent sampling moments in the two-dimensional power flow field to form a dynamic power track line; Based on the space density of the dynamic power track line, automatically generating a non-uniform triangular grid in a two-dimensional power flow field domain to cover the dynamic power track line, wherein the vertex density of the triangular grid is positively correlated with the local curvature of the dynamic power track line, and the triangular grid is an adaptive grid topology for adjusting the vertex position and connection relation of the triangular grid along with the change of power state points.
3. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-connected converter according to claim 2, wherein the generating a dynamic power streamline between nodes of the adaptive grid topology according to a voltage instantaneous value sequence and a current instantaneous value sequence comprises: For each triangular grid unit of the self-adaptive grid topology, calculating gradient vectors of active power instantaneous values and reactive power instantaneous values corresponding to three vertexes of the triangular grid unit; Carrying out weighted average on gradient vectors of three vertexes in each triangular grid unit to obtain a power flow direction vector of the triangular grid unit; And drawing a streamline pointing to the low-power density area from the high-power density area on the self-adaptive grid topology along the vector field of the power flow direction, wherein the streamline is a dynamic power streamline representing the real-time power transmission path and the strength.
4. A distribution network low voltage flexible interconnection control method for a grid-connected converter as claimed in claim 3, wherein said tracking and capturing curvature jump events of said dynamic power flow lines comprises: Calculating the local curvature of each dynamic power streamline with a fixed step length along each dynamic power streamline to form a curvature sequence of the dynamic power streamline; applying sliding window differential operation to the curvature sequence, detecting a moment point in which a differential value in the curvature sequence exceeds a mutation detection threshold value, and marking the moment as the occurrence moment of a curvature mutation event; And tracing back to the occurrence time, intercepting dynamic power streamline fragments in a preset time window before and after the occurrence time, and simultaneously recording triangular grid cell sets in the self-adaptive grid topology penetrated by the dynamic power streamline fragments, wherein the dynamic power streamline fragments and the triangular grid cell sets jointly form a power disturbance feature packet.
5. The method for controlling low-voltage flexible interconnection of a distribution network of a network-structured converter according to claim 1, wherein the driving a power controller based on field deformation feedback with the power disturbance feature packet as input comprises: carrying out time-frequency joint analysis on waveform fragments in the power disturbance characteristic package, and extracting dominant distortion frequency components and distortion energy duty ratio in a time spectrum of the waveform fragments as distortion mode characteristics; Analyzing an adaptive grid topological area in a power disturbance feature packet, and calculating the standard deviation of the side lengths and the variation range of the inner angles of all triangular grid units in the adaptive grid topological area to be used as a topological stress distribution feature; The deformation mode characteristics and the topological stress distribution characteristics are input into a pre-trained deformation decision network, the deformation decision network outputs deformation instructions for applying stretching, compressing or shearing to a target area of the self-adaptive grid topology, deformation amplitude and direction corresponding to each deformation instruction, and the deformation amplitude and direction corresponding to each deformation instruction form a field compensation deformation instruction together.
6. The method for controlling low-voltage flexible interconnection of a distribution network of a network-structured converter according to claim 5, wherein the method for controlling the low-voltage flexible interconnection of the distribution network based on the field compensation deformation instruction specifically comprises: According to the field compensation deformation instruction, applying corresponding compensation deformation to the self-adaptive grid topology in a power flow field, and generating new dynamic power streamline distribution by the self-adaptive grid topology after the compensation deformation; identifying a steady-state power channel in the new dynamic power streamline distribution, the steady-state power channel being defined by a curvature of the dynamic power streamline continuously below a steady-state threshold; Mapping the steady-state power channel back to an electric quantity space, and converting the steady-state power channel into a steady-state voltage amplitude instruction and a phase angle instruction; Meanwhile, carrying out harmonic mode stripping on the real-time electrical waveform to separate a fundamental wave energy mode and a residual harmonic oscillation mode; the steady-state power signal defined by the steady-state voltage amplitude command and the phase angle command is subjected to waveform fusion with the residual harmonic oscillation mode to synthesize a converter modulation wave signal; and generating driving pulses of the grid-structured converter according to the converter modulation wave signals, and realizing control of low-voltage flexible interconnection of the distribution network.
7. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-structured converter according to claim 6, wherein the applying corresponding compensation deformation to the adaptive grid topology in a power flow field according to a field compensation deformation instruction specifically comprises: Positioning a target area designated by a field compensation deformation instruction in a two-dimensional power flow field, wherein the target area is identified by a triangular grid unit; According to the deformation type and the deformation amplitude in the field compensation deformation instruction, synchronously transforming the vertex coordinates of all triangular grid units in the target area; After the vertex coordinates are transformed, recalculating and updating the connection relation and geometric parameters of all affected triangular grid units, and completing the construction of the self-adaptive grid topology after the compensation deformation; the identifying a steady-state power channel in the new dynamic power streamline distribution specifically comprises: regenerating a dynamic power streamline on the self-adaptive grid topology after the deformation compensation; Monitoring curvature change of a newly generated dynamic power streamline in a preset observation time period, and judging that a certain section of dynamic power streamline is a steady-state power channel if the curvature maximum value of the section of dynamic power streamline in the whole observation time period is continuously lower than a steady-state threshold value; and recording the initial point coordinates and the end point coordinates of all the steady-state power channels in the two-dimensional power flow field and the passing grid cell sequence.
8. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-connected converter as set forth in claim 7, wherein said mapping the steady-state power channel back to the electrical space is converted into steady-state voltage amplitude command and phase angle command, comprising: For each steady-state power channel, calculating the average active power value and the average reactive power value of the steady-state power channel in a two-dimensional power flow field according to the initial point coordinate and the end point coordinate of the steady-state power channel; And converting the average active power value and the average reactive power value into a steady-state voltage amplitude instruction of the target node and a phase angle instruction relative to the public coupling point through a preset power-to-voltage mapping relation.
9. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-connected converter according to claim 6, wherein the step of performing harmonic mode stripping on the real-time electrical waveform to separate a fundamental wave energy mode and a residual harmonic oscillation mode comprises the steps of: Applying adaptive noise complete set empirical mode decomposition to the voltage instantaneous value sequence and the current instantaneous value sequence to obtain a series of eigenmode functions; According to the instantaneous frequency of the eigenmode function, eigenmode function components with the instantaneous frequency around power frequency fluctuation are screened out, and the components are reconstructed into fundamental wave energy modes; Subtracting the fundamental wave energy mode from the original real-time electric waveform, and obtaining the residual waveform component as a residual harmonic oscillation mode.
10. The method for controlling low-voltage flexible interconnection of a distribution network of a grid-connected converter according to claim 6, wherein the step of performing waveform fusion on a steady-state power signal defined by a steady-state voltage amplitude command and a phase angle command and a residual harmonic oscillation mode to synthesize a converter modulated wave signal comprises the steps of: generating a power frequency sinusoidal reference voltage waveform as a steady-state power signal according to the steady-state voltage amplitude command and the phase angle command; the steady-state power signal and the residual harmonic oscillation mode are overlapped point by point on the time domain to obtain an initial modulation wave; And performing amplitude limiting and smoothing filtering treatment on the initial modulation wave to ensure that the amplitude of the initial modulation wave is in a linear modulation region of the converter and the waveform is continuously conductive, wherein the processed waveform is the converter modulation wave signal finally used for generating driving pulse.

Description

Distribution network low-voltage flexible interconnection control method for grid-structured converter Technical Field The invention relates to the technical field of flexible control of power distribution networks, in particular to a distribution network low-voltage flexible interconnection control method of a constructed network type converter. Background In modern distribution networks with distributed energy high penetration access, achieving flexible power interdependence and voltage support between multiple low voltage interconnection points is a key challenge. The prior art relies mainly on a centralized or distributed control strategy based on a fixed electrical parametric model. These methods are generally optimized at a predetermined operating point or typical topology, and the generation of control commands relies on periodic sampling and calculation of voltage, current efficiency, or fundamental power. Another common idea is to use event-driven based control, where the triggering condition is mostly out of limit of the electrical quantity threshold. These conventional schemes have limitations in facing short-term, nonlinear disturbances such as abrupt load changes, intermittent power supply switching, etc. The fixed model is difficult to accurately describe a dynamic power flow path under real-time coupling of system topology and running state, so that the control action is poor in prospective and accuracy. The control based on threshold triggering belongs to post-regulation, has weak identification capability on disturbance modes, cannot distinguish disturbance sources from propagation characteristics, and is easy to cause redundancy of regulation or response lag. A method capable of deeply fusing real-time dynamic characteristics of a power grid and performing advanced or collaborative refined control according to the real-time dynamic characteristics is needed, so that autonomous sensing and self-adaptive cancellation capability of a flexible interconnection system on complex disturbance situations is improved. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a distribution network low-voltage flexible interconnection control method of a grid-connected converter. In order to achieve the purpose, the invention adopts the following technical scheme that the distribution network low-voltage flexible interconnection control method of the grid-connected converter comprises the following steps: Acquiring real-time electrical waveforms of a plurality of interconnection points in a low-voltage power distribution network, wherein the real-time electrical waveforms comprise a voltage instantaneous value sequence and a current instantaneous value sequence; Injecting the real-time electrical waveform into a power flow field domain for dynamic analysis, constructing an adaptive grid topology which is deformed along with the change of the running state of the power distribution network in the power flow field domain, and generating a dynamic power streamline between nodes of the adaptive grid topology according to a voltage instantaneous value sequence and a current instantaneous value sequence; Tracking and capturing curvature abrupt change events of the dynamic power streamline, and when the local curvature of the dynamic power streamline exceeds a preset curvature threshold, extracting waveform fragments of the dynamic power streamline and an adaptive grid topological area to which the waveform fragments belong to form a power disturbance feature packet; The power disturbance feature packet is taken as input, a power controller based on field deformation feedback is driven, and the power controller based on the field deformation feedback outputs a field compensation deformation instruction according to the distortion mode of waveform fragments in the power disturbance feature packet and the stress distribution of the self-adaptive grid topological area; and based on the field compensation deformation instruction, the control of the low-voltage flexible interconnection of the distribution network is realized. As a further aspect of the present invention, the dynamically analyzing the real-time electrical waveform injected into a power flow field, and constructing an adaptive grid topology in the power flow field, the adaptive grid topology deforming with the change of the operation state of the power distribution network, includes: Calculating an active power instantaneous value and a reactive power instantaneous value at each sampling moment according to the voltage instantaneous value sequence and the current instantaneous value sequence; Constructing a two-dimensional power flow field domain by taking an active power instantaneous value as a horizontal axis coordinate and a reactive power instantaneous value as a vertical axis coordinate, and drawing a power state point at each sampling moment in the two-dimensional power flow field domain; connecting powe