Zhao X.,Tsinghua University |
Chen Y.,SiYuan Electrical Co. |
Liu W.,Tsinghua University |
Zhang X.,SiYuan Electrical Co. |
Li G.,SiYuan Electrical Co.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014
A new topology is proposed for the unbalance load compensation of cascaded STATCOM with star configuration, which connects the neutral point of an additional grounding transformer with STATCOM to form the pass of zero-sequence current needed by negative-sequence compensation. The way to generate the reference current and the zero-sequence current is explained by the power analysis and the method to control the DC voltage balance among phases is deduced. Simulative and experimental results show that, with the proposed topology and control method, the negative-sequence current of load is preferably compensated and the DC voltage balance among phases preferably satisfied. Engineering analysis shows that, compared with the Δ/Y configuration, the proposed configuration is more cost-effective and space-effective.
Jing Y.,Shenyang University of Technology |
Li Y.,Shenyang University of Technology |
Eerhemubayaer,Siyuan Electrical Co.
Gaodianya Jishu/High Voltage Engineering | Year: 2012
In order to analyze the leakage magnetic field and eddy current losses in large-scale power transformer, taking the nonlinear magnetic B-H characteristics of core, tank and magnetic shield material into account, we computed the leakage magnetic field and eddy current loss in tank, yoke clamps, and other conductive construction parts of high voltage auto-transformer by three-dimensional (3D) nonlinear time harmonic finite element method. The results show that eddy current losses and loss density in tank wall and yoke clamps are large, may cause local overheating, and affect normal operation of the transformer. The magnetic shields added to tank wall and yoke clamps were used to reduce the eddy current loss in tank wall and yoke clamps of power transformer, and effects of those shields on leakage magnetic field and eddy current loss of construction parts were discussed. The results show that eddy current losses and hot spots can be reduced and eliminated effectively by adding magnetic shield to tank wall and yoke clamps. The different types of shields have different influences on leakage magnetic field and eddy current losses in construction parts of transformer.