摘要
在传统附加频率控制策略下,多端柔性直流(VSC-MTDC)系统调节交流侧频率易引起较大的直流电压波动。文章提出一种基于虚拟惯性频率调节的VSC-MTDC系统自适应下垂控制策略。首先,通过虚拟惯性频率调节控制,建立直流侧电压与交流侧频率的联系,使VSC-MTDC系统为交流电网频率提供惯性响应,提高系统频率稳定性。其次,考虑换流器的调节裕度,并引入直流电压影响因子,使下垂系数随着直流电压偏差实时变化,由此建立有功功率、直流电压和交流侧频率三者之间的耦合关系,实现VSC-MTDC系统对频率提供惯性支撑,同时保障直流电压稳定。最后,基于PSCAD/EMTDC电磁暂态仿真平台建立四端VSC-MTDC输电系统,并选取交流电网负荷减少、负荷增加和发生瞬时短路故障3种工况,验证了所提控制策略的可行性和有效性。
With the traditional additional frequency control strategy,due to the fixed droop coefficient,the voltage source converter multi terminal direct current(VSC-MTDC)transmission system is prone to cause large DC voltage fluctuation in the process of AC side frequency regulation,which endangers the safety of equipment operation.To solve this problem,a VSC-MTDC system adaptive droop control strategy based on virtual inertia frequency adjustment was proposed.Firstly,the connection between the DC side voltage and the AC side frequency is established through the virtual inertia frequency adjustment control,so that the VSC-MTDC system provides an inertial response to the AC grid frequency and improves the system frequency stability.Then,considering the adjustment margin of the converter station and introduce the DC voltage influence factor,the droop coefficient changes in real time with the DC voltage deviation,and from this,the coupling relationship between active power,DC voltage and AC side frequency are obtained to realize that VSC-MTDC system provides inertial support for the frequency while ensuring the stability of the DC voltage.Finally,based on the PSCAD/EMTDC electromagnetic transient simulation platform,a four-terminal VSC-MTDC transmission system was established,and three operating conditions of AC grid load reduction,AC grid load increase and AC grid transient short-circuit fault are selected to verify the feasibility of the proposed control strategy.
作者
刘英培
石金鹏
梁海平
杨博超
Liu Yingpei;Shi Jinpeng;Liang Haiping;Yang Bochao(School of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071003,China)
出处
《可再生能源》
CAS
CSCD
北大核心
2022年第8期1081-1088,共8页
Renewable Energy Resources
基金
国家自然科学基金项目(51607069)。
关键词
多端柔性直流输电
虚拟惯性频率调节
自适应下垂控制策略
直流电压稳定
voltage source converter multi-terminal DC
virtual inertial frequency regulation
improved droop control
DC voltage stability
