Startup Inrush Current Suppression Method for Star-connected CHB STATCOM

doi:10.11985/2022.01.010

Abstract

Abstract:

Soft startup is essential to the operation of the star-connected cascaded H-bridge (CHB) STATCOM. Conventional CHB STATCOM startup strategy suppresses inrush current by connecting current limiting resistors in series during uncontrolled rectification. However, due to the low DC-side capacitor voltage after the start-up phase, the CHB STATCOM will still generate a large inrush current when it enters the normal operating state. To eliminate this inrush current, a novel startup control is proposed to further charge the DC voltages after the uncontrolled rectifier process. After the uncontrolled rectification stage, the controllable boost stage is introduced, and the current limiting resistors continues to be connected in series, thereby further increasing the DC capacitor voltage. In the controllable boost stage, the relationship between modulation voltages and DC voltages is established, based on which a closed-loop control is proposed. The effectiveness of the proposed control is verified by the experimental results on a 400 V/5 kVar CHB STATCOM.

Key words: CHB STATCOM, current limiting resisters, inrush current, startup control

CLC Number:

TM561

WU Tianhong, WEI Miaoyu, LU Daorong, HU Haibing. Startup Inrush Current Suppression Method for Star-connected CHB STATCOM[J]. Journal of Electrical Engineering, 2022, 17(1): 71-77.

Figures/Tables 14

References 25

[1]	MAHARJAN L, TAJYUTA T, MARUYAMA K, et al. Development and verification test of the 6.6-kV 200-kVA transformerless SDBC-based STATCOM using SiC-MOSFET modules[J]. IEEE Trans. Power Electron., 2020, 35(12):13687-13696. doi: 10.1109/TPEL.2020.2995159
[2]	RAMOS E R, LEYVA R, FARIVAR G G, et al. Incremental passivity control in multilevel cascaded H-bridge converters[J]. IEEE Trans. Power Electron., 2020, 35(8):8766-8788. doi: 10.1109/TPEL.2020.2965164
[3]	WU Siqi, LIU Zhigang. Low-frequency stability analysis of vehicle-grid system with active power filter based on dq-frame impedance[J]. IEEE Trans. Power Electron., 2021, 36(8):9027-9040. doi: 10.1109/TPEL.2021.3049145
[4]	HASHEMZADEH E, KHEDERZADEH M, AGHAMOHAMMADI M R, et al. A robust control for D-STATCOM under variations of DC-link capacitance[J]. IEEE Trans. Power Electron., 2021, 36(7):8325-8333. doi: 10.1109/TPEL.2020.3026092
[5]	SHI Youjie, LIU Bangyin, SHI Yanjun. Individual phase current control based on optimal zero-sequence current separation for a star-connected cascade STATCOM under unbalanced conditions[J]. IEEE Trans. Power Electron., 2016, 31(3):2099-2110. doi: 10.1109/TPEL.2015.2442528
[6]	LU Daorong, WANG Jiangfeng, YAO Jianhui, et al. Clustered voltage balancing mechanism and its control strategy for star-connected cascaded H-bridge STATCOM[J]. IEEE Trans. Ind. Electron., 2017, 64(10):7623-7633. doi: 10.1109/TIE.2017.2694390
[7]	LU Daorong, ZHU Jianxin, WANG Jiangfeng, et al. A simple zero-sequence-voltage-based cluster voltage balancing control and the negative sequence current compensation region identification for star-connected cascaded H-bridge STATCOM[J]. IEEE Trans. Power Electron., 2018, 33(10):8376-8387.
[8]	YU Y, KONSTANTINOU G, TOWNSEND C D, et al. Comparison of zero-sequence injection methods in cascaded H-bridge multilevel converters for large-scale photovoltaic integration[J]. IET Renewable Power Gener., 2017, 11(5):603-613. doi: 10.1049/iet-rpg.2016.0621
[9]	LIU Bi, SONG Wensheng, LI Ryan Yunwei, et al. Performance improvement of DC capacitor voltage balancing control for cascaded H-bridge multilevel converters[J]. IEEE Trans. Power Electron., 2021, 36(3):3354-3366. doi: 10.1109/TPEL.2020.3012540
[10]	WANG Mingda, ZHANG Xing, TAO Zhao, et al. Harmonic compensation strategy for single-phase cascaded H-bridge PV inverter under unbalanced power conditions[J]. IEEE Trans. Ind. Electron., 2020, 67(12):10474-10484. doi: 10.1109/TIE.2019.2962461
[11]	AKAGI H, INOUE S, YOSHII T. Control and performance of a transformerless cascade PWM STATCOM with star configuration[J]. IEEE Transactions on Industry Applications, 2007, 43(4):1041-1049. doi: 10.1109/TIA.2007.900487
[12]	DEKKA A, WU B, ZARGARI N R. Start-up operation of a modular multilevel converter with flying capacitor submodules[J]. IEEE Trans. Power Electron., 2017, 32(8):5873-5877. doi: 10.1109/TPEL.2017.2660399
[13]	ELSEROUGI A, MASSOUD A M, AHMED S. A modular high-voltage pulse-generator with sequential charging for water treatment applications[J]. IEEE Trans. Ind. Electron., 2016, 63(12):7898-7907. doi: 10.1109/TIE.2016.2515055
[14]	GONZALEZ-HERNANDO F, SAN-SEBASTIAN J, GARCIA-BEDIAGA A, et al. Wear-out condition monitoring of IGBT and mosfet power modules in inverter operation[J]. IEEE Trans. Ind. Appl., 2019, 55(6):6184-6192. doi: 10.1109/TIA.2019.2935985
[15]	XU Jianzhong, ZHAO Chengyong, ZHANG Baoshun, et al. New precharge and submodule capacitor voltage balancing topologies of modular multilevel converter for VSC-HVDC application[C]// Proc. Asia-Pac. Power Energy Eng. Conf., 2011:1-4.
[16]	TIAN Kai, WU Bin, DU Sixing, et al. A simple and cost-effective precharge method for modular multilevel converters by using a low-voltage DC source[J]. IEEE Trans. Power Electron., 2016, 31(7):5321-5329. doi: 10.1109/TPEL.2015.2484222
[17]	DUARTE S N, ALMEIDA P M, BARBOSA P G, et al. A novel energizing strategy for a grid-connected modular multilevel converter operating as static synchronous compensator[J]. Int. J. Elect. Power Energy Syst., 2019, 109(10):672-684. doi: 10.1016/j.ijepes.2019.02.028
[18]	PUGLIESE S, BUTICCHI G, MASTROMAURO A R, et al. Soft-start procedure for a three-stage smart transformer based on dual-active bridge and cascaded H-bridge converters[J]. IEEE Trans. Power Electron., 2020, 35(10):11039-11052. doi: 10.1109/TPEL.2020.2977226
[19]	GU G, CHOI J H, JUNG I S. Start-up current control method for three-phase PWM rectifiers with a low initial DC-link voltage[J]. J. Power Electron., 2012, 12(4):587-594. doi: 10.6113/JPE.2012.12.4.587
[20]	NOVIĆ M M. Startup procedure for DSP-controlled three-phase six-switch boost PFC rectifier[J]. IEEE Trans. Power Electron., 2015, 30(8):4514-4523. doi: 10.1109/TPEL.2014.2351752
[21]	LI Binbin, XU Dandan, ZHANG Yi, et al. Closed-loop precharge control of modular multilevel converters during start-up processes[J]. IEEE Trans. Power Electron., 2015, 30(2):524-531. doi: 10.1109/TPEL.2014.2334055
[22]	SHI Xiaojie, LIU Bo, WANG Zhiqiang, et al. Modeling,control design, and analysis of a startup scheme for modular multilevel converters[J]. IEEE Trans. Ind. Electron., 2015, 62(11):7009-7024. doi: 10.1109/TIE.2015.2436354
[23]	WANG Jinyu, TANG Yi, QI Yang, et al. A unified startup strategy for modular multilevel converters with deadbeat predictive current control[J]. IEEE Trans. Ind. Electron., 2021, 68(8):6401-6411. doi: 10.1109/TIE.2020.3007080
[24]	ZHANG Lei, QIN Jiangchao, WU Xiajie, et al. A generalized precharging strategy for soft startup process of the modular multilevel converter-based HVDC systems[J]. IEEE Trans. Ind. Appl., 2017, 53(6):5645-5657. doi: 10.1109/TIA.2017.2736958
[25]	LU Daorong, WANG Sen, YAO Jianhui, et al. Cluster voltage regulation strategy to eliminate negative-sequence currents under unbalanced grid for star-connected cascaded H-bridge STATCOM[J]. IEEE Trans. Power Electron., 2019, 34(3):2193-2205. doi: 10.1109/TPEL.2018.2844544

参数	数值
网侧线电压幅值E_m/V	400
输出无功功率Q/kVar	5
直流侧电容容值C/mF	3
直流侧电容电压U_norm/V	85
交流侧电感阻抗L/mH	6
限流电阻阻值R/Ω	20
每相级联模块数N	5