Load Current Feedforward Control Strategy for Power Electronic Transformer

doi:10.11930/j.issn.1004-9649.202103009

Abstract

Abstract: Power Electronic Transformer (PET) consists of cascaded H-bridge (CHB) converters and dual active bridge (DAB) converters. However, the fluctuation of load causes large voltage fluctuation of high voltage DC (HVDC) and low voltage DC (LVDC) buses of PET. To address this problem, a load current feedforward control strategy for cascaded systems is proposed, which consists of two parts: the load current feedforward of DAB stage and CHB stage. The former obtains the compensated phase shift ratio of the DAB stage through calculation of the load current at the low voltage side, while the latter feeds forward the load current to the CHB stage with consideration of the power conservation of the cascade system. Moreover, considering the delay of the inner current loop of the CHB stage, the first order differential is introduced to the feedforward strategy in CHB stage, which further suppresses the voltage fluctuation on HVDC buses. The proposed control strategy only needs to sample the load current of LVDC bus, which saves the system cost greatly. In addition, the proposed strategy is easy to operate and implement. Simulation and Starsim experimental results verify the correctness and effectiveness of the proposed control method.

Key words: power electronic transformer, cascaded H-bridge, dual active bridge converter, voltage fluctuation, feedforward control

LI Shuaihu, WANG Tingting, LIU Zhi, PENG Hanmei, TANG Kun. Load Current Feedforward Control Strategy for Power Electronic Transformer[J]. Electric Power, 2022, 55(9): 88-97.

Add to citation manager EndNote|Ris|BibTeX

URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.202103009

https://www.electricpower.com.cn/EN/Y2022/V55/I9/88

References

[1] 段青, 盛万兴, 李振, 等. 电能路由器接入电力电子化配电网稳定性初步分析[J]. 电网技术, 2019, 43(1): 227–235
DUAN Qing, SHENG Wanxing, LI Zhen, et al. Stability analysis of power routers connected to power electronic distribution grid[J]. Power System Technology, 2019, 43(1): 227–235
[2] HUBER J E, KOLAR J W. Solid-state transformers: on the origins and evolution of key concepts[J]. IEEE Industrial Electronics Magazine, 2016, 10(3): 19–28.
[3] 翟少磊, 张学志, 段怡, 等. 基于交直流微电网的智慧能源站拓扑结构研究[J]. 智慧电力, 2021, 49(5): 28–34
ZHAI Shaolei, ZHANG Xuezhi, DUAN Yi, et al. Topology structure of smart energy station based on AC/DC microgrid[J]. Smart Power, 2021, 49(5): 28–34
[4] 陈龙龙, 徐飞, 魏晓光, 等. 大容量可控关断的直流输电用电流源型换流器研究综述[J]. 中国电力, 2021, 54(1): 23–36
CHEN Longlong, XU Fei, WEI Xiaoguang, et al. A review on large capacity controllable switching current source converter research[J]. Electric Power, 2021, 54(1): 23–36
[5] 乔丽, 王航, 谢剑, 等. 同步调相机对分层接入特高压直流输电系统的暂态过电压抑制作用研究[J]. 中国电力, 2020, 53(3): 43–51
QIAO Li, WANG Hang, XIE Jian, et al. Suppressing effect of synchronous condenser on transient overvoltage of UHVDC system under hierarchical connection mode[J]. Electric Power, 2020, 53(3): 43–51
[6] 孔祥平, 李鹏, 韩杰祥, 等. 适应电力电子变压器功率双向交换的低电压穿越运行控制策略[J]. 电力科学与技术学报, 2021, 36(2): 124–131
KONG Xiangping, LI Peng, HAN Jiexiang, et al. Low-voltage ride through strategy for bidirectional power electronic transformers[J]. Journal of Electric Power Science and Technology, 2021, 36(2): 124–131
[7] 徐冬冬, 张国澎, 黄凯. 新一代高压变频器混合型整流级直流电压脉动研究[J]. 电力系统保护与控制, 2020, 48(15): 43–49
XU Dongdong, ZHANG Guopeng, HUANG Kai. DC-line ripple of hybrid rectifier stage in a new generation of high-voltage inverter[J]. Power System Protection and Control, 2020, 48(15): 43–49
[8] ZHAO B, SONG Q, LI J G, et al. High-frequency-link DC transformer based on switched capacitor for medium-voltage DC power distribution application[J]. IEEE Transactions on Power Electronics, 2016, 31(7): 4766–4777.
[9] CUI F J, SETHUPANDI A, FARIVAR G, et al. Study of some operational degrees of freedom for cascaded AC-DC converters in solid state transformer[C]//2019 10 th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia). Busan, Korea (South). IEEE, 2019: 2448-2453.
[10] 王杉杉, 王玉斌, 林意斐, 等. 级联型电力电子变压器电压与功率均衡控制方法[J]. 电工技术学报, 2016, 31(22): 92–99
WANG Shanshan, WANG Yubin, LIN Yifei, et al. Voltage and power balance control for cascaded multilevel converter based power electronic transformer[J]. Transactions of China Electrotechnical Society, 2016, 31(22): 92–99
[11] YANG J X, LIU J Q, ZHANG J P, et al. Research on different balance control strategies for a power electronic traction transformer[C]//2018 IEEE Applied Power Electronics Conference and Exposition. San Antonio, TX, USA. IEEE, 2018: 1821–1828.
[12] XIAO F, TU C M, GE Q, et al. Ripple voltage suppression and control strategy for CHB-based solid-state transformer[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(1): 1104–1118.
[13] LIU J Q, YANG J X, ZHANG J P, et al. Voltage balance control based on dual active bridge DC/DC converters in a power electronic traction transformer[J]. IEEE Transactions on Power Electronics, 2018, 33(2): 1696–1714.
[14] 段青, 乐健, 吕志鹏, 等. 利用电能路由器的配电网电能质量控制[J]. 电测与仪表, 2017, 54(14): 57–63
DUAN Qing, YUE Jian, LV Zhipeng, et al. Power quality control method in distribution network based on power router[J]. Electrical Measurement & Instrumentation, 2017, 54(14): 57–63
[15] 许峰, 姜军. 电力电子变压器改善电能质量的仿真研究[J]. 机电信息, 2018(36): 4–6
[16] 徐少博, 陈嘉敏, 徐永海, 等. 级联型电力电子变压器三相电压暂降隔离能力分析[J]. 电力系统自动化, 2020, 44(4): 168–177
XU Shaobo, CHEN Jiamin, XU Yonghai, et al. Analysis on three-phase voltage sag isolation capability of cascaded power electronic transformer[J]. Automation of Electric Power Systems, 2020, 44(4): 168–177
[17] SHE X, HUANG A Q, NI X J. Current sensorless power balance strategy for DC/DC converters in a cascaded multilevel converter based solid state transformer[J]. IEEE Transactions on Power Electronics, 2014, 29(1): 17–22.
[18] WANG R, SUN Q Y, ZHANG X M, et al. The impedance-based stability analysis of the single-phase solid state transformer[C]//2018 Chinese Automation Congress (CAC). Xi'an, China. IEEE, 2018: 35–40.
[19] 孙玉巍, 李永刚, 刘教民, 等. 级联式电力电子变压器协调控制策略[J]. 中国电机工程学报, 2018, 38(5): 1290–1300
SUN Yuwei, LI Yonggang, LIU Jiaomin, et al. Coordinative control strategy for cascaded power electronic transformer[J]. Proceedings of the CSEE, 2018, 38(5): 1290–1300
[20] WANG F, HUANG A, WANG G Y, et al. Feed-forward control of solid state transformer[C]//2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition. Orlando, FL, USA. IEEE, 2012: 1153–1158.
[21] SHAN Z Y, JATSKEVICH J, IU H H C, et al. Simplified load-feedforward control design for dual-active-bridge converters with current-mode modulation[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2018, 6(4): 2073–2085.
[22] 王成山, 李霞林, 郭力. 基于功率平衡及时滞补偿相结合的双级式变流器协调控制[J]. 中国电机工程学报, 2012, 32(25): 109–117
WANG Chengshan, LI Xialin, GUO Li. Coordinated control of two-stage power converters based on power balancing and time-delay compensation[J]. Proceedings of the CSEE, 2012, 32(25): 109–117
[23] 李沫霖, 郭志强. 负载电流前馈闭环控制的快速动态响应双有源桥式变换器的输出阻抗分析[J]. 电源学报, 2020, 18(3): 55–62
LI Molin, GUO Zhiqiang. Output impedance analysis of dual active bridge converter with load current feedforward closed-loop control for fast dynamic response[J]. Journal of Power Supply, 2020, 18(3): 55–62
[24] 阳建, 刘勇, 盘宏斌, 等. 基于虚拟同步机的微网逆变器无频差控制[J]. 电网技术, 2016, 40(7): 2001–2008
YANG Jian, LIU Yong, PAN Hongbin, et al. Method of frequent deviation-free control of microgrid inverter based on virtual synchronous generator control[J]. Power System Technology, 2016, 40(7): 2001–2008
[25] LIU Z, LI S H, XIAO F, et al. Adaptive control strategy of solid state transformer with fast dynamic response and enhanced balance performance[J]. IET Power Electronics, 2022, 15(4): 306–316.