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Method and system for determining stability of flexible direct-current small interference

A flexible DC and stability technology, applied in the direction of DC network circuit devices, AC network circuits, power transmission AC networks, etc., can solve the problems of not being able to truly reflect the dynamic characteristics of the flexible DC transmission system, ignoring the dynamic characteristics of flexible DC

Active Publication Date: 2019-11-19
CHINA ELECTRIC POWER RES INST +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, most of the calculation methods considering the small-disturbance stability characteristics of the flexible DC transmission system are to regard the flexible DC transmission system as a load according to the power equivalent, and then use the load as a part of the AC grid to participate in the small-disturbance stability calculation of the AC grid. The disadvantage is that the dynamic characteristics of flexible DC are completely ignored
In addition, there are some related studies that have established small-signal models of flexible DC transmission systems to obtain more accurate calculation results, but these models have done a lot for the Phase-Locked Loop (PLL) Very simplified modeling, small disturbance and stable calculation results cannot truly reflect the dynamic characteristics of the flexible HVDC system

Method used

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  • Method and system for determining stability of flexible direct-current small interference
  • Method and system for determining stability of flexible direct-current small interference
  • Method and system for determining stability of flexible direct-current small interference

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Embodiment 1

[0130] The invention relates to a method for judging the stability influence of soft and straight small disturbances, such as figure 1 The one shown includes the following steps:

[0131] Step 1: Obtain the parameters, measured values ​​and AC grid voltage of the flexible direct current transmission system;

[0132] Step 2: constructing a state matrix based on the given formula of the flexible DC transmission system based on the parameters, measured values ​​and AC grid voltage, and calculating the eigenvalues ​​of the state matrix;

[0133] Step 3: When the AC system is connected, the small-disturbance stability of the flexible direct current transmission system is determined according to the eigenvalues ​​of the state matrix.

[0134] Step one includes the following:

[0135] Step1: Obtain the following parameters according to the design scheme of the flexible DC converter and its controller and phase-locked loop:

[0136] Rectifier bridge arm resistance, denoted as R 1 ...

Embodiment 2

[0296] Set the amplification factor k of the proportional link in the phase-locked loop device p,pll The range of change is 1-100.

[0297] If the flexible DC transmission system is connected to the AC system with strong voltage support capability, k p,pll The trajectory curve of the eigenvalues ​​of matrix A when changing within this range is as follows figure 1 shown, from figure 2 It can be seen that the eigenvalue of the matrix A always has a real part less than zero, indicating that the HVDC flexible system is stable with little disturbance within this parameter range;

[0298] If the flexible DC transmission system is connected to the AC system with weak voltage support capability, k p,pll The trajectory curve of the eigenvalues ​​of matrix A when changing within this range is as follows image 3 shown, from image 3 It can be seen that k p,pll p,pll = 43, matrix A has eigenvalues ​​equal to zero real part, k p,pll >43, the matrix A has eigenvalues ​​with a real ...

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Abstract

The invention provides a method and a system for determining the stability of flexible direct-current small interference. The method comprises the following steps of: acquiring parameters, measured values and the alternating-current power grid voltage of a flexible direct-current power transmission system; constructing a state matrix according to the parameters, the measured values and the AC power grid voltage based on a given formula of the flexible DC power transmission system, and calculating characteristic values of the state matrix; and when an alternating current system is accessed, determining the small interference stability of the flexible direct current power transmission system according to the characteristic value of the state matrix. The method can truly reflect the dynamic characteristics of the flexible DC power transmission system, is high in accuracy, and can analyze the impact on the small-interference stability of the flexible DC power transmission system from the change of the control parameters of the phase-locked loop and the impact on the control parameters of the flexible DC power transmission system when different AC systems are connected.

Description

Technical field: [0001] The invention relates to the technical field of power system operation and planning, in particular to a method and system for judging the stability of flexible DC small disturbances. Background technique: [0002] The traditional thyristor-based DC power transmission system is sensitive to the influence of the AC system, and it is easy to cause commutation failure due to AC side disturbances. At the same time, it can only work in the active inverter state and consumes a lot of reactive power. Flexible DC transmission (voltage source converter based high-voltage DC, VSC-HVDC) technology can effectively solve these defects by virtue of its own characteristics, and the research on VSC-HVDC technology is gradually becoming a hot spot in the research of DC transmission technology. Flexible DC transmission projects can be connected to weak AC systems or passive systems. Therefore, VSC-HVDC systems have broad application prospects in new energy access, islan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J1/00H02J3/36
CPCH02J1/00H02J3/36H02J2003/365Y02E60/60
Inventor 姜懿郎张君成郭小江施浩波高超丁平张玉红
Owner CHINA ELECTRIC POWER RES INST
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