Abstract：Aiming at the abnormal condition of unbalanced grid voltage, the grid side of RMC has double frequency power pulsation. The active and reactive power in RMC cannot track the power reference value at the same time, whose pulsation cannot also be eliminated using the instantaneous reactive power control strategy of traditional direct power prediction, thus leads to current distortion in grid side and instability in DC side. The topology of RMC is different from the three-phase PWM rectifier because a high-frequency transformer is used to couple the front and rear stages. The method is not applicable completely. Therefore, the problem of larger pulsation it must be solved. In order to solve the above problems, this paper proposes an extended direct power predictive control method in an RMC system. Firstly, the double frequency fluctuation expressions of active and reactive power under unbalanced input voltage are derived and analyzed. The positive and negative sequence components of grid voltage and current are extracted by using the quarter grid cycle delay method. Secondly, an extended instantaneous power theory more suitable for unbalanced power grid is introduced, and a model predictive extended power control method is proposed. By reconstructing the reference value of instantaneous power, the self-suppression of grid side power and DC voltage ripple fluctuation is realized. Then, aiming at the problem that the input active power still contains large pulsation when the extended power predictive control under unbalanced grid voltage, the adjacent two-beat error of the active power is added to the cost function on the minimum cost function of the model predictive control to reduce the error of active power tracking. The new cost function is constructed to suppress the input active power pulsation and suppress the grid side current distortion under unbalanced grid voltage conditions. Finally, the effectiveness of proposed method was verified in an RMC experimental prototype. A comparative experiment between the traditional direct power predictive control method and the proposed extended direct power predictive control method is designed. The experimental results show that the active power double frequency fluctuation amplitude of direct power predictive control under unbalanced grid voltage is 5.8 V, the reactive power fluctuation amplitude is 6 V, the fluctuation amplitude is 7.4 V, and the grid current THD is 7.41 %. Under the extended power predictive control, the active power fluctuation amplitude is 4 V, the fluctuation amplitude is reduced by 31.03 %, and the reactive power fluctuation amplitude is 5.8 V, the fluctuation amplitude is reduced by 3.33 %. The output voltage fluctuation amplitude is 5.4 V, and the fluctuation amplitude is reduced by 27.03 %. The sinusoidal grid side current and unit power factor operation of RMC are realized, which verifies the effectiveness and correctness of the proposed method. This paper draws the following conclusions : (1)Under unbalanced grid conditions, the proposed method can effectively suppress the fluctuation of input current, output power and output DC voltage caused by unbalanced grid voltage. (2) The complex weighting factor selection is not required for the cost function using proposed method. (3)The power factor in grid side is closer to unity comparing the direct power predictive control.
韩思鹏, 宋卫章, 胥少杰, 李佳耿, 杜晓斌. 不平衡电网电压下精简矩阵变换器扩展直接功率模型预测控制[J]. 电工技术学报, 2023, 38(zk1): 147-156.
Han Sipeng, Song Weizhang, Xu Shaojie, Li Jiageng, Du Xiaobin. Extended Direct Power Model Predictive Control for Reduced Matrix Converter Under Unbalanced Grid Voltage Operation Condition. Transactions of China Electrotechnical Society, 2023, 38(zk1): 147-156.
[1] 宋卫章, 刘江, 孙向东, 等. 基于模型预测控制的三相-一相矩阵变换器偏磁控制[J]. 电工技术学报, 2019, 34(12): 2489-2498. Song Weizhang, Liu Jiang, Sun Xiangdong et al. Research on bias control of 3 phase-1 phase matrix converter based on model predictive control[J]. Transactions of China Electrotechnical Society, 2019, 34(12): 2489-2498. [2] Wodyk S, Iwanski G.Vibrating coordinates frame transformation based unity power factor control of a three-phase converter at grid voltage imbalance and harmonics[J]. IEEE Transactions on Industrial Electronics, 2021, 69(2): 1114-1123. [3] Guo Leilei, Jin Nan, Li Yanyan, et al.A model predictive control method for grid-connected power converters without AC voltage sensors[J]. IEEE Transactions on Industrial Electronics, 2021, 68(2): 1299-1310 [4] Nguyen T L, Lee H H.An enhanced control strategy for AC-DC matrix converters under unbalanced grid voltage[J]. IEEE Transactions on Industrial Electronics, 2020, 67(3): 1718-1727. [5] 梅杨, 许策, 鲁乔初. 基于零矢量嵌入的双向隔离型AC-DC矩阵变换器分段同步控制策略[J]. 电工技术学报, 2021, 36(22): 4784-4794. Mei Yang, Xu Ce, Lu Qiaochu.Piecewise synchronous control strategy of bidirectional isolated matrix AC-DC converter based on zero vector embedded[J]. Transactions of China Electrotechnical Society, 2021, 36(22): 4784-4794. [6] Lei Jiaxing, Feng Shuang, Wheeler P, et al.Steady-state error suppression and simplified implementation of direct source current control for matrix converter with model predictive control[J]. IEEE Transactions on Power Electronics, 2020, 35(3): 3183-3194. [7] Zheng Liran, Kandula R P, Divan D.Robust predictive control for modular solid-state transformer with reduced DC link and parameter mismatch[J]. IEEE Transactions on Power Electronics, 2021, 36(12): 14295-14311. [8] 张永昌, 彭玉宾, 曲昌琦, 等. 不平衡电网电压下的PWM整流器预测电流控制[J]. 电工技术学报, 2016, 31(4): 88-94, 103. Zhang Yongchang, Peng Yubin, Qu Changqi, et al.Predictive current control of PWM rectifier under unbalanced grid voltage condition[J]. Transactions of China Electrotechnical Society, 2016, 31(4): 88-94, 103. [9] 朱进权, 葛琼璇, 王晓新, 等. 基于自抗扰和负载功率前馈的高速磁悬浮系统PWM整流器控制策略[J]. 电工技术学报, 2021, 36(2): 320-329. Zhu Jinquan, Ge Qiongxuan, Wang Xiaoxin, et al.Control strategy for PWM rectifier of high-speed maglev based on active disturbance rejection control and load power feed-forward[J]. Transactions of China Electrotechnical Society, 2021, 36(2): 320-329. [10] 杨美辉, 周念成, 王强钢, 等.基于分布式协同的双极直流微电网不平衡电压控制策略[J]. 电工技术学报, 2021, 36(3): 634-645. Yang Meihui, Zhou Niancheng, Wang Qianggang, et al.Unbalanced voltage control strategy of bipolar DC microgrid based on distributed cooperation[J]. Transactions of China Electrotechnical Society, 2021, 36(3): 634-645. [11] 姚绪梁, 罗兴鸿, 马赫, 等. 小电容双PWM调速系统直流母线电压波动抑制策略[J]. 电工技术学报, 2022, 37(12): 2971-2981. Yao Xuliang, Luo Xinghong, Ma He, et al.DC bus voltage fluctuation suppression strategy for small capacitance dual-PWM speed regulating system[J]. Transactions of China Electrotechnical Society, 2022, 37(12): 2971-2981. [12] 江畅, 程启明, 马信乔, 等. 不平衡电网电压下基于模块化多电平变流器的统一电能质量调节器的微分平坦控制[J]. 电工技术学报, 2021, 36(16): 3410-3421. Jiang Chang, Cheng Qiming, Ma Xinqiao, et al.Differential flat control for unified power quality controller based on modular multilevel converter under unbalanced grid voltage[J]. Transactions of China Electrotechnical Society, 2021, 36(16): 3410-3421. [13] Ran Xiaohong, Xu Bo, Liu Kaipei, et al.An improved low-complexity model predictive direct power control with reduced power ripples under unbalanced grid conditions[J]. IEEE Transactions on Power Electronics, 2022, 37(5): 5224-5234. [14] Wu Fengjiang, Li Xiaoguang, Wang Guizhong, et al.Analysis of effect of grid harmonics and unbalance on DAB-based three-phase single-stage AC-DC converter and solutions[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022, 10(1): 1192-1202. [15] Chen Qiang, Xu Jianping, Huang Rui, et al.A digital control strategy with simple transfer matrix for three-phase Buck rectifier under unbalanced AC input conditions[J]. IEEE Transactions on Power Electronics, 2021, 36(4): 3661-3666. [16] 张建辉, 许莹莹, 李云丰. 交流电网不平衡下铁路功率调节器负序电流完全补偿策略研究[J]. 中国电机工程学报, 2020, 40(10): 3144-3154. Zhang Jianhui, Xu Yingying, Li Yunfeng, et al.Completed compensation strategy research of railway power conditioner for negative-sequence current under unbalanced AC power grids[J]. Proceedings of the CSEE, 2020, 40(10): 3144-3154. [17] 王金浩, 李胜文, 常潇, 等. 电压不平衡条件下电动汽车充电机电流分析模型[J]. 电工技术学报, 2021, 36(增刊2): 582-590. Wang Jinhao, Li Shengwen, Chang Xiao, et al.Electric vehicle charger current analysis model under unbalanced voltage[J]. Transactions of China Electrotechnical Society, 2021, 36(S2): 582-590. [18] Rahoui A, Bechouche A, Seddiki H, et al.Virtual flux estimation for sensorless predictive control of PWM rectifiers under unbalanced and distorted grid conditions[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(2): 1923-1937. [19] Yang Haitao, Zhang Yongchang, Liu Jie.Frequency-Adaptive virtual flux estimator-based predictive power control with suppression of dc voltage ripples under unbalanced network[J]. IEEE Transactions on Industrial Electronics, 2020, 67(10): 8969-8979. [20] Nguyen T L, Lee H H.An enhanced control strategy for AC-DC matrix converters under unbalanced grid voltage[J]. IEEE Transactions on Industrial Electronics, 2020, 67(3): 1718-1727. [21] 宋金秋, 段彬, 付程, 等. 电网不平衡工况下高频链矩阵变换器非线性反步控制策略[J]. 中国电机工程学报, 2022, 42(2): 761-772. Song Jinqiu, Duan Bin, Fu Cheng, et al.Completed compensation strategy research of railway power conditioner for negative-sequence current under unbalanced AC power grids[J]. Proceedings of the CSEE, 2022, 42(2): 761-772. [22] Ran Xiaohong, Xu Bo, Liu Kaipei.A novel framework of extended active power and its application into low complexity MPC for enhanced steady-state performance[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022, 10(5): 5647-5658. [23] Sun Dan, Wang Xiaohe, Nian Heng, et al.A sliding-mode direct power control strategy for DFIG under both balanced and unbalanced grid conditions using extended active power[J]. IEEE Transactions on Power Electronics, 2018, 33(2): 1313-1322. [24] 李山, 马雯, 郭强, 等. 非理想电网条件下PWM整流器优化预测功率控制[J]. 电工技术学报, 2022, 37(18): 4745-4756. Li Shan, Ma Wen, Guo Qiang, et al.Optimal predictive power control of PWM rectifier under nonideal grid conditions[J]. Transactions of China Electrotechnical Society, 2022, 37(18): 4745-4756.
2023, Vol. 38 
