DC-Link Capacitance Design for Cascaded H-Bridge STATCOM With Sum of Squares Formulation
DC-Link Capacitance Design for Cascaded H-Bridge STATCOM With Sum of Squares Formulation
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DOI：
10.1109/tpel.2024.3365178
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发表时间：
2024-05
影响因子：
6.7
通讯作者：
Hengyi Wang;Junyi Zhang;Xingxiao Xia;Fei Gao;Jianqiang Cheng
中科院分区：
文献类型：
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作者：
Hengyi Wang;Junyi Zhang;Xingxiao Xia;Fei Gao;Jianqiang Cheng
本文提出了一种用于静态同步补偿器 (STATCOM) 的三角形连接级联 H 桥 (CHB) 的通用电容器选型方法，该方法可以在电容、电感和谐波模式下运行。选型方法考虑了电能质量、峰值和峰峰值电容器电压限制。通过将正弦和余弦变换为正切，将限制表述为非负单变量多项式。由于多项式系数与电容值相关，因此可行的电容值保证了多项式系数的非负性。由于非负性和平方和 (SOS) 等效，因此将 SOS 程序与迭代算法相结合来找到最小电容。此外，还给出了选择平均电容器电压的指南。所提出的电容尺寸确定方法不需要近似，因此是准确的。与现有的容性/感性模式的电容选型方法相比，本文提出的方法的另一个特点是即使STATCOM工作在谐波模式下也能够确定电容值。当电网出现不平衡/谐波电压等故障时，该方法也是可行的。进行了全面的仿真和实验，显示了所提出的电容尺寸确定方法的有效性和准确性。
This article has proposed a generic capacitor sizing method for delta-connected cascaded H-bridge (CHB) used for static synchronous compensator (STATCOM), which can be operated in capacitive, inductive, and harmonic modes. The sizing method takes power quality, peak, and peak-to-peak capacitor voltage limitations into consideration. By transforming the sines and cosines into tangent, the limitations are formulated as nonnegative univariate polynomials. Because the polynomials coefficients are related with the capacitance value, a feasible capacitance value guarantees their nonnegativity. Since nonnegativity and sum of squares (SOS) are equivalent, the SOS program is combined with an iterative algorithm to find the minimal capacitance. Moreover, a guide for selecting the average capacitor voltage is given. The proposed capacitance sizing method does not need approximation, therefore it is accurate. Compared with the existing capacitance sizing methods for the capacitive/inductive mode, another feature of the method raised in this article is that it is able to determine the capacitance value even if STATCOM is operated in harmonic mode. The proposed method is also feasible when grid faults, such as unbalanced/harmonic voltages, appear. Comprehensive simulations and experiments are conducted, showing the effectiveness and accuracy of the proposed capacitance sizing method.