Abstract：Series-parallel compensated uninterruptible power supply (UPS), as a new UPS, consists of back-to-back bidirectional converters, and can achieve power flow control and four-quadrant 360 degree operation. Based on the principle of power balance of gird and load side, the power flow mechanism of series-parallel compensated UPS is analyzed in detail in this paper with grid voltage fluctuations. The two converters can cooperatively work. One operates in the rectifier state, and the other operates in the inverter state, so that the inadequate or excess energy can be regulated. Meanwhile, the compensated UPS can achieve the gird side unit power factor and stable sinusoidal output voltage. The four-quadrant operation mechanism of series-parallel compensated UPS under different load conditions is analyzed in detail, and the phasor diagrams of resistance, capacitive and inductive load are obtained. Hence, the operating region state diagrams are obtained. The operation angle ranges of series-parallel compensated UPS are thereafter determined. Finally, the theoretical analysis is verified by simulation and experiment.
[1] 霍群海, 韩立博, 韦统振, 等. D-FACTS装置交互影响分析及协调控制研究[J]. 电工技术学报, 2015, 30(1): 329-336. Huo Qunhai, Han Libo, Wei Tongzhen, et al. Study on the interaction and coordinated operation of D-FACTS[J]. Transactions of China Electrotechnical Society, 2015, 30(1): 329-336. [2] 贾清泉, 于浩, 邬小波. 电能质量状态空间表示及其应用[J]. 燕山大学学报, 2016, 40(3): 219-224. Jia Qingquan, Yu Hao, Wu Xiaobo. A power quality state space representation and its application[J]. Journal of Yanshan University, 2016, 40(3): 219- 224. [3] 张新闻, 同向前. 电容耦合型动态电压恢复器参数建模与控制[J]. 电工技术学报, 2016, 31(6): 212- 218. Zhang Xinwen, Tong Xiangqian. Parameter modeling and control of capacitor-coupled dynamic voltage restorer[J]. Transactions of China Electrotechnical Society, 2016, 31(6): 212-218. [4] Ali Y G, Hossein S, Sabahi M, et al. Three-phase HFL-DVR with independently controlled phases[J]. IEEE Transactions on Power Electronics, 2012, 27(4): 1706-1718. [5] 李哲, 吴正国, 夏立, 等. 任意负载条件下动态电压恢复器的复合谐振控制策略[J]. 中国电机工程学报, 2013, 33(25): 130-138. Li Zhe, Wu Zhengguo, Xia Li, et al. Compound resonant control for dynamic voltage restorers under arbitrary load conditions[J]. Proceedings of the CSEE, 2013, 33(25): 130-138. [6] 唐君华, 涂春鸣, 姜飞, 等. 限流式动态电压恢复器及其参数设计[J]. 电力系统保护与控制, 2015, 43(24): 115-121. Tang Junhua, Tu Chunming, Jiang Fei, et al. Dynamic voltage restorer with current limiting function and its parameter design[J]. Power System Protection and Control, 2015, 43(24): 115-121. [7] 陆晶晶, 肖湘宁, 张剑, 等. 基于定有功电流限值控制的MMC型UPQC协调控制方法[J]. 电工技术学报, 2015, 30(3): 196-205. Lu Jingjing, Xiao Xiangning, Zhang Jian, et al. MMC-UPQC coordinated control method based on fixed active current limit value control[J]. Transa- ctions of China Electrotechnical Society, 2015, 30(3): 196-205. [8] Silva S A O D, Barriviera R, Modesto R A, et al. Single-phase power quality conditioners with series- parallel filtering capabilities[C]//IEEE International Symposium on Industrial Electronics (ISIE), Gdansk, 2011: 1124-1130. [9] Rodrigo A M, Barriviera R, Silva S A O D, et al. A simplified strategy used to control the output voltage and the input current of a single-phase line- interactive UPS system[C]//Brazilian Power Electronics Conference (COBEP), Gramado, 2013: 420-426. [10] 王浩, 刘进军, 梅桂华. 配网统一电能质量控制器直流电容的容量计算与分析[J]. 电力系统保护与控制, 2014, 42(9): 14-19. Wang Hao, Liu Jinjun, Mei Guihua. Calculation and analysis of DC capacitor capacitance in distribution UPQC[J]. Power System Protection and Control, 2014, 42(9): 14-19. [11] Khadkikar V. Enhancing electric power quality using UPQC: a comprehensive overview[J]. IEEE Transa- ctions on Power Electronics, 2012, 27(5): 2284-2297. [12] Sérgio Augusto Oliveira da Silva, Rodrigo Augusto Modesto. Active power line compensation applied to a three-phase line interactive UPS system using SRF method[C]//IEEE 36th Power Electronics Specialists Conference, Aachen, 2005: 2358-2362. [13] Tan Zhili, Zhu Dongjiao. Study of detection method of the waveform compensation component of UPQC with improved p-q-r theory[C]//Asia-Pacific Power and Energy Engineering Conference, Wuhan, 2011: 1-4. [14] Khadkikar V, Chandra A. A novel control approach for unified power quality conditioner-Q without active power injection for voltage sag compensation[C]// IEEE International Conference on Industrial Tech- nology (ICIT), Mumbai, 2006: 779-784. [15] Lee W C, Lee D M, Lee T K. New control scheme for a unified power quality compensator-Q with minimum active power injection[J]. IEEE Transactions on Power Delivery, 2010, 25(2): 1068-1076. [16] 谭智力, 朱冬姣, 陈坚. 一种三相四线统一电能质量调节器的零稳态误差控制策略[J]. 电工技术学报, 2011, 26(10): 77-82. Tan Zhili, Zhu Dongjiao, Chen Jian. A new zero steady-state error control strategy used in three-phase four-wire UPQC[J]. Transactions of China Electro- technical Society, 2011, 26(10): 77-82.
2017, Vol. 32 
