摘要
在基于模块化多电平流器的多端柔性直流输电(modular multi-level converter based multi-terminal high voltage direct current system,MMC-MTDC)系统中,PI双环解耦的直接电流控制(double-loop direct current,DLDC)无法为系统提供惯性,而常规虚拟同步发电机(conventional virtual synchronous generator,CVSG)控制虽然能为系统提供惯性支撑,实现对交流系统的一次调频,但仍属于频率有差调节,未能充分发挥换流器的灵活调节的优点。针对上述问题,结合MMC-MTDC系统功率-电压的改进下垂控制方法,提出了一种改进虚拟同步发电机(improved virtual synchronous generator,IVSG)的受端换流器控制策略。该策略在保留CVSG控制中的惯性参数和阻尼参数的基础上,引入频率偏差的积分控制,使换流器参与交流系统二次调频工作,通过与其他受端换流器的协调配合,实现对交流系统频率的无差控制。基于Opal-RT仿真平台,搭建包含集群风场在内的5端31电平MMC-MTDC输电系统模型,设计MMC-MTDC系统不同的运行工况,对所提出的控制策略进行仿真验证。仿真结果表明,在直流系统功率发生波动时,所提控制策略具有合理分配受端功率、增加换流器惯性和参与交流系统二次调频的能力。
In modular multi-level converter based multi-terminal HVDC system(MMC-MTDC), PI double-loop direct current(DLDC) control cannot provide inertia for the system. Although conventional virtual synchronous generator(CVSG) control can provide inertia for the system and realize primary frequency regulation of AC system, it still belongs to differential frequency regulation and fails to give full play to the advantage of flexible regulation of converter. To address this issue, combined with the improved droop control(IDC) method of MMC-MTDC system, this paper proposes an improved virtual synchronous generator(IVSG) converter control strategy. Based on retaining the inertia and damping parameters in CVSG control, frequency deviation is introduced into the integral controller to make the converter participate in the secondary frequency regulation of AC system, and realize deviation-free frequency control of AC system through coordinating with other converters. To verify the proposed control strategy, a model of 5-terminal 31-level MMC-MTDC system interconnected with wind farm is built on Opal-RT simulator, and different operating conditions of the MMCMTDC system are designed. Simulation results show that the proposed control strategy can reasonably distribute the received power, increase the inertia of converter and participate in secondary frequency regulation of AC system when the power of DC system fluctuates.
作者
陈继开
曾强
辛业春
王振浩
李国庆
CHEN Jikai;ZENG Qiang;XIN Yechun;WANG Zhenhao;LI Guoqing(School of Electrical Engineering,Northeast Electric Power University,Jilin 132012,Jilin Province,China)
出处
《电网技术》
EI
CSCD
北大核心
2020年第4期1428-1436,共9页
Power System Technology
基金
国家电网公司总部科技项目(5102-201999343A-0-0-00)。.
关键词
模块化多电平换流器
虚拟同步发电机
频率调节
无差控制
多端柔性直流输电
modular multilevel converter
virtual synchronous generator(VSG)
frequency regulation
deviation-free control
multi-terminal HVDC system(MTDC)
