CN-122000922-A - Self-adaptive series impedance compensation method considering bidirectional power flow characteristics

CN122000922ACN 122000922 ACN122000922 ACN 122000922ACN-122000922-A

Abstract

The invention discloses a self-adaptive series impedance compensation method considering bidirectional power flow characteristics, which belongs to the technical field of power distribution network voltage control and comprises the steps of collecting voltage signals and current signals of a public connection point in a line in real time, calculating active power and reactive power of the line, calculating virtual impedance compensation quantity required to be connected in series according to the active power and the reactive power, judging a power flow direction according to the flow direction of the active power, determining the positive and negative polarities of the virtual impedance compensation quantity according to the power flow direction, determining drop voltage based on the virtual impedance compensation quantity, and performing voltage compensation. The invention not only solves the problem of bidirectional limit crossing of steady-state voltage caused by the reverse transmission of distributed power supply power, but also ensures the accurate and stable voltage of the tail end of the power distribution network.

Inventors

LU YONG
Xiang Ziran
Xia Shenao
ZHANG ZHEN
XU XIANFENG
WU CHUNLING

Assignees

长安大学

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (9)

1. An adaptive series impedance compensation method taking bidirectional power flow characteristics into consideration, comprising: Collecting voltage signals and current signals of a public connection point in a line in real time, and calculating active power and reactive power of the line; Calculating virtual impedance compensation quantity required to be connected in series according to the active power and the reactive power; Judging a power flow direction according to the flow direction of active power, and determining the positive and negative polarities of the virtual impedance compensation quantity according to the power flow direction; determining a drop voltage based on the virtual impedance compensation amount, and performing voltage compensation; Wherein the virtual impedance compensation amount includes a virtual resistance compensation amount and a virtual reactance compensation amount; according to the active power and the reactive power, calculating the virtual impedance compensation quantity needed to be connected in series, comprising the following steps: Calculating a base virtual resistance compensation amount based on the active power and an inverse droop coefficient of the virtual resistance compensation amount; calculating a base virtual reactance compensation amount based on the reactive power and an inverse droop coefficient of the virtual reactance compensation amount; And respectively carrying out nonlinear correction on the basic virtual resistance compensation quantity and the basic virtual reactance compensation quantity to obtain the virtual resistance compensation quantity and the virtual reactance compensation quantity which need to be connected in series.
2. The adaptive series impedance compensation method considering bidirectional power flow characteristics according to claim 1, wherein the basic virtual resistance compensation amount is calculated according to the following formula: ; in the formula, An inverse droop coefficient representing the virtual resistance compensation amount, Which represents the active power of the electric motor, Representing the basic virtual resistance compensation amount.
3. The adaptive series impedance compensation method considering bidirectional power flow characteristics according to claim 2, wherein the basic virtual reactance compensation amount is calculated according to the following formula: ; in the formula, An inverse droop coefficient representing the virtual reactance compensation amount, Which represents the reactive power of the power plant, Representing the basic virtual reactance compensation amount.
4. The adaptive series impedance compensation method according to claim 3, wherein the step of respectively performing nonlinear correction on the basic virtual resistance compensation amount and the basic virtual reactance compensation amount to obtain a virtual resistance compensation amount and a virtual reactance compensation amount to be connected in series, comprises: multiplying the first nonlinear correction term by the basic virtual resistance compensation quantity to obtain a virtual resistance compensation quantity to be connected in series The first nonlinear correction term is composed of a basic compensation gain constant Active power load factor-based secondary correction term And an active power based triangle correction term Constructing; multiplying the second nonlinear correction term by the basic virtual reactance compensation quantity to obtain a virtual reactance compensation quantity to be connected in series The second nonlinear correction term is formed by basic compensation gain constant Reactive power load factor-based secondary correction term And a delta correction term based on reactive power The composition is formed.
5. The adaptive series impedance compensation method considering bi-directional power flow characteristics according to claim 4, wherein said first nonlinear correction term is expressed as: Wherein, the ; ; ; ; ; In the formula, For a preset constant for controlling the amplitude of the voltage compensation, The power factor angle is represented as such, Indicating the power factor of the access load, The active power at which the line end voltage drops by 10% relative to the nominal end voltage is indicated.
6. The adaptive series impedance compensation method considering bi-directional power flow characteristics according to claim 4, wherein said second nonlinear correction term is expressed as: Wherein, the ; ; ; ; ; In the formula, For a preset constant for controlling the amplitude of the voltage compensation, The reactive power at which the line end voltage drops by 10% relative to the rated end voltage is indicated.
7. The adaptive series impedance compensation method considering bidirectional power flow characteristics according to claim 1, wherein the step of determining a power flow direction from a flow direction of active power and determining positive and negative polarities of the virtual impedance compensation amount from the power flow direction comprises: Active power When the current forward power flow working condition is judged, the virtual impedance compensation quantity is configured to be of negative polarity; Active power When the current reverse power flow working condition is judged, the virtual impedance compensation quantity is configured to be positive in characteristic; the positive polarity characteristic of the virtual impedance compensation quantity is used for increasing the equivalent impedance of the line to inhibit voltage rise under the reverse power flow working condition, and the negative polarity characteristic of the virtual impedance compensation quantity is used for counteracting the line impedance to compensate voltage drop under the forward power flow working condition.
8. The adaptive series impedance compensation method considering bidirectional power flow characteristics according to claim 1, wherein the step of determining a sag voltage based on the virtual impedance compensation amount and performing voltage compensation comprises: Virtual resistance compensation amount which is connected in series according to requirement And virtual reactance compensation amount And (3) calculating the drop voltage: ; in the formula, Which represents the active power of the electric motor, Which represents the reactive power of the power plant, Representing the line-end voltage (v-v) and, The resistance of the line is indicated and, Representing the reactance of the line, Representing a drop voltage; according to drop voltage And performing voltage compensation.
9. The adaptive series impedance compensation method according to claim 8, wherein the step-down voltage is based on the bidirectional power flow characteristics Before the step of performing voltage compensation, the method further comprises: Judging Whether the preset range is larger than the preset range; if yes, according to the drop voltage Determining a synchronization signal : ; In the formula, , Representing preset fine tuning times; If synchronous signal Increasing the virtual impedance compensation amount according to a first preset step length, if the synchronous signal Reducing the virtual impedance compensation amount according to a second preset step length; calculating the drop voltage according to the trimmed virtual impedance compensation amount And return the judgment Whether the number of times of fine tuning is larger than a preset range or not until the preset number of times of fine tuning is reached Or (b) Less than or equal to a preset range.

Description

Self-adaptive series impedance compensation method considering bidirectional power flow characteristics Technical Field The invention belongs to the technical field of power distribution network voltage control, and particularly relates to a self-adaptive series impedance compensation method considering bidirectional power flow characteristics. Background As the permeability of new energy sources such as distributed photovoltaic, wind power and the like in a power distribution network continuously rises, the power distribution network gradually evolves from a traditional unidirectional radial network to an active power distribution network with multi-source characteristics. The structural transformation brings remarkable bidirectional power flow characteristics that when the output of the distributed power supply exceeds a local load, the voltage at the tail end of a feeder line is raised due to power reversal, and when the illumination is insufficient or the load is high, voltage drop is caused by forward power flow. Particularly, in a medium-low voltage distribution network, the line impedance presents high resistance ratio characteristics, so that the voltage is extremely sensitive to fluctuation of active power, and the reactive power regulation is simply relied on to make a half of effort. In view of the above challenges, conventional voltage management approaches have significant limitations. OLTC (on-load TAP CHANGER, on-load tap changing transformer) is limited by the number of mechanical switch actions and response speed, and is difficult to cope with frequent voltage fluctuation of minute level and even second level caused by randomness of new energy output. Although the response speed of reactive compensation devices based on parallel connection, such as SVG (STATIC VAR Generator ) and D-STATCOM (Distributed Static Synchronous Compensator, distributed static synchronous compensator), is fast, in a high-impedance-ratio line, the efficiency of adjusting the voltage only by injecting reactive power is low due to the dominant effect of the line resistance, and the problem of voltage out-of-limit caused by active power dumping cannot be effectively restrained. In addition, the existing series voltage compensation device such as DVR (Dynamic Voltage Restorer ) has the capability of directly injecting voltage vector, but the traditional control strategy is designed for voltage sag under unidirectional tide or specific sensitive load protection, the self-adaptive capability of bidirectional power flow working condition of the distribution network is generally lacking, the impedance characteristic cannot be dynamically adjusted according to the change of the power flow direction, and the expected treatment effect is difficult to achieve when the problem of steady-state voltage bidirectional out-of-limit caused by high-permeability new energy access is solved. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a self-adaptive series impedance compensation method considering bidirectional power flow characteristics. The technical problems to be solved by the invention are realized by the following technical scheme: the invention provides a self-adaptive series impedance compensation method considering bidirectional power flow characteristics, which comprises the following steps: Collecting voltage signals and current signals of a public connection point in a line in real time, and calculating active power and reactive power of the line; Calculating virtual impedance compensation quantity required to be connected in series according to the active power and the reactive power; Judging a power flow direction according to the flow direction of active power, and determining the positive and negative polarities of the virtual impedance compensation quantity according to the power flow direction; And determining a longitudinal component of the voltage drop based on the virtual impedance compensation amount, and performing voltage compensation. Compared with the prior art, the invention has the beneficial effects that: (1) The invention provides a self-adaptive series impedance compensation method considering bidirectional power flow characteristics, which is characterized in that the active power and the reactive power of a circuit are calculated by collecting voltage signals and current signals of a public connection point in the circuit in real time, the power flow direction is identified based on the active power, and the positive and negative polarities of virtual impedance compensation quantity are configured according to the active power. (2) The nonlinear correction term comprising the secondary correction term and the triangular correction term is constructed, so that the defect of insufficient adaptability of the existing linear anti-sagging control in the whole working condition range is overcome, the nonlinear voltage drop characteristic of a light load area