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Flexible DC transmission dynamic stability determining and controlling method

A flexible DC power transmission and dynamic stability technology, applied in the direction of AC power input conversion to DC power output, AC network circuit, AC power input conversion to AC power output, etc. Conducive to engineering practice, the method is simple and easy to implement

Active Publication Date: 2019-04-19
SICHUAN UNIV
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Problems solved by technology

[0008] 2) Through the impedance modeling of the system, whether the input impedance characteristic of the system is negative is used to judge whether the system is stable. First, the overall modeling is required; : Wu Wenhua, Chen Yandong, Luo An, Zhou Leming, Zhou Xiaoping, Yang Ling, Huang Xucheng. DC Impedance Modeling, Oscillation Analysis and Suppression Methods of Island VSC-HVDC Transmission System. Proceedings of the Chinese Society for Electrical Engineering, 2018, 38(15):4359-4368+ 4636. "A Virtual Resistor Current Limit Control Method for Suppressing Continuous Commutation Failure in Traditional DC Transmission")

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  • Flexible DC transmission dynamic stability determining and controlling method
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  • Flexible DC transmission dynamic stability determining and controlling method

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[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. A method for judging the dynamic stability of flexible direct current transmission in the present invention comprises the following steps:

[0030] Step 1: Unlock the converter station of the HVDC system, so that the HVDC system operates in a non-islanding control mode; Step 2: Extract the corresponding parameters of the HVDC system, the parameters include the effective value of the AC system voltage U t0 , flexible DC output reactive power Q vsc0 , the gain k of the phase-locked loop PLL p and the proportional-integral time constant k of the phase-locked loop PLL i ;Step 3: Taking the rated capacity of the converter station and the AC system voltage as the reference value, calculate the short-circuit ratio SCR, and calculate U t0 , Q vsc0 The per unit value of ; Step 4: Calculate the key stable component where ω is the angular fr...

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Abstract

The invention discloses a flexible DC transmission dynamic stability determining and controlling method which comprises the steps of: unlocking a converter station of a flexible DC transmission system, and allowing the flexible DC transmission system to operate in a non-island control mode; extracting corresponding parameters of the flexible DC transmission system, wherein the parameters include an AC system voltage effective value Ut0, a flexible DC external reactive power Qvsc0, a gain kp of a phase locked loop PLL, and a proportional integral time constant ki of the phase locked loop PLL; calculating a short-circuit ratio SCR, the per-unit value of Ut0 and Qvsc0; calculating a key stable component; and checking the sign of the key stable component and determining the stability of the flexible DC transmission system. The method of the invention only needs to simply calculate the value of the key stable component, determines the stability of the system by the sign of the value, is simple and easy, and is beneficial to engineering practice.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission system control, in particular to a method for judging and controlling the dynamic stability of flexible direct current transmission. Background technique [0002] Compared with traditional LCC-HVDC, flexible direct current transmission VSC-HVDC can provide reactive power support for AC system without commutation failure, so it has wider application prospects in weak connection scenarios. In particular, in the island control mode (constant AC voltage, constant AC frequency), it can realize new functions that conventional transmission methods do not have, such as flexible grid connection of new energy, power transmission to passive systems, and auxiliary grid black start. [0003] When the VSC-HVDC is connected in parallel with the AC system, the system frequency is determined by the AC main network. At this time, the VSC must adopt the non-islanding control mode, but it...

Claims

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Application Information

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IPC IPC(8): H02J3/36
CPCH02J3/36Y02E60/60H02M5/4585H02J2003/365H02M7/7575
Inventor 李保宏刘天琪陶艳
Owner SICHUAN UNIV
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