Control Strategy of Seamless Switching for VSG Grid-Connected/Islanded Based on Virtual Current

doi:10.16628/j.cnki.2095-8188.2020.11.010

Abstract

Abstract:

The control strategy of micro-grid inverter based on virtual synchronous generator (VSG) technology can increase the inertia and damping of the system to a certain extent,which further improves the grid-connected absorbing ability of distributed power.There are two operating modes of the micro-grid:connected and off-grid,but there will be a large impulse current at the moment of on-off switching.Therefore,a control strategy of seamless switching for VSG grid-connected/islanded based on virtual current is proposed.This article first establishes the mathematical model of VSG,designs its power frequency regulator and excitation controller module.Secondly,it analyzes the problems that occur during the on and off-grid switching of VSG,and then proposes an improved pre-synchronous control strategy to ensure the smooth switching of VSG between the two operating modes.Finally,the simulation model is built using MATLAB/Simulink to verify the correctness of the proposed strategy.

Key words: micro-grid, seamless switching, virtual synchronous generator (VSG), virtual current, presynchronization

CLC Number:

TM464

LIN Lei, WEN Buying. Control Strategy of Seamless Switching for VSG Grid-Connected/Islanded Based on Virtual Current[J]. LOW VOLTAGE APPARATUS, 2020, 0(11): 58-64.

Figures/Tables 14

References 23

[1]	曾正, 赵荣祥, 唐盛清, 等. 可再生能源分散接入用先进并网逆变器研究综述[J]. 中国电机工程学报, 2013,33(24):1-12.
[2]	邓建玲. 能源互联网的概念及发展模式[J]. 电力自动化设备, 2016,36(3):1-5.
[3]	王成山, 李鹏. 分布式发电、微网与智能配电网的发展与挑战[J]. 电力系统自动化, 2010,34(2):10-14.
[4]	魏昊焜, 刘健, 高慧. 分布式电源的本地电压控制策略[J]. 电力自动化设备, 2016,36(9):40-45.
[5]	BLAABJERG F, TEODORESCU R, LISERRE M, et al. Overview of control and grid synchronization for distributed power generation systems[J]. IEEE Transactions on Industrial Electronics, 2006,53(5):1398-1409.
[6]	HOU X, HAN H, ZHONG C, et al. Improvement of transient stability in inverter-based AC microgrid via adaptive virtual inertia:2016 IEEE Energy Conversion Congress and Exposition (ECCE)[C]. 2016.
[7]	陈昕, 张昌华, 黄琦, 等. 引入功率微分项下垂控制的逆变器并联系统小信号稳定性分析[J]. 电网技术, 2016,40(11):3467-3473.
[8]	陈虹妃, 张宸宇, 缪恵宇, 等. 虚拟同步机控制策略与下垂控制的比较[J]. 电器与能效管理技术, 2018 (15):25-31.
[9]	郑天文, 陈来军, 陈天一, 等. 虚拟同步发电机技术及展望[J]. 电力系统自动化, 2015,39(21):165-175.
[10]	曾正, 邵伟华, 冉立, 等. 虚拟同步发电机的模型及储能单元优化配置[J]. 电力系统自动化, 2015,39(13):28-37.
[11]	ZHONG Q C, NGUYEN P L, MA Z Y, et al. Self-synchronized synchronverters:inverters without a dedicated synchronization unit[J]. IEEE Transactions on Power Electronics, 2014,29(2):617-630. doi: 10.1109/TPEL.2013.2258684
[12]	张宸宇, 杨赟, 袁晓冬, 等. 考虑阻尼和惯性的虚拟同步机建模方法研究[J]. 电力工程技术, 2018,37(5):45-49.
[13]	支琴, 吴映阳, 金之俭. 基于虚拟同步发电机控制并网逆变器的研究与设计[J]. 电器与能效管理技术, 2017(20):56-62.
[14]	张宸宇, 邓凯, 史明明, 等. 微电网中基于虚拟同步发电机技术的变换器[J]. 电器与能效管理技术, 2017(3):9-13.
[15]	ZHONG Q C, WEISS G. Synchronverters:inverters that mimic synchronous generators[J]. IEEE Trans on Industrial Electronics, 2011,58(4):1259-1267. doi: 10.1109/TIE.2010.2048839
[16]	郭权利, 苑舜, 周春阳, 等. 基于模糊控制的微网平滑切换控制策略的研究[J]. 高电压技术, 2015,41(10):3281-3287.
[17]	王劲松, 唐成虹, 陈娜, 等. 基于运行模式自识别的微电网并离网平滑切换控制策略[J]. 电力系统自动化, 2015,39(9):185-191.
[18]	聂志强, 梁晖, 罗浩, 等. 基于非线性下垂控制的单模式微网并/离网无缝切换技术[J]. 电网技术, 2016,40(5):1371-1378. doi: 10.13335/j.1000-3673.pst.2016.05.012
[19]	石荣亮, 张兴, 徐海珍, 等. 基于虚拟同步发电机的微网运行模式无缝切换控制策略[J]. 电力系统自动化, 2016,40(10):16-23.
[20]	吕志鹏, 盛万兴, 钟庆昌, 等. 虚拟同步发电机及其在微电网中的应用[J]. 中国电机工程学报, 2014,34(16):2591-2603. doi: 10.13334/j.0258-8013.pcsee.2014.16.009
[21]	徐晓宁, 周雪松. 微网脱/并网运行模式平滑切换控制策略[J]. 高电压技术, 2018,44(8):2754-2760.
[22]	何亮, 王劲松. 三相PWM逆变器输出LC滤波器设计方法[J]. 电气传动, 2013,43(12):33-36.
[23]	吴恒, 阮新波, 杨东升, 等. 虚拟同步发电机功率环的建模与参数设计[J]. 中国电机工程学报, 2015,35(24):6508-6518. doi: 10.13334/j.0258-8013.pcsee.2015.24.027

参数	数值
直流电压U_dc/V	800
电网电压U_g/V	220
滤波电感L₁/mH	2
滤波电容C₁/μF	40
虚拟惯量J/(kg·m²)	0.45
阻尼系数D_p/(Nm·s·rad^-1)	30