Control method of three-level neutral-point-clamped inverter based on voltage vector diagram partition

A new modulation approach was presented for the control of neutral-point (NP) voltage variation in the three-level NP-clamped voltage source inverter, and the average NP current model was established based on vector diagram partition. Thus, theory base was built for balancing control of NP potential. Theoretical analysis and experimental results indicate that the proposed method for NP balancing control vector synthesizing concept based can make the average NP current zero, and do not influence NP potential within every sample period. The effectiveness of proposed research approach was verified by simulative and experimental results.     

Theoretical studies of active power/angle sub-matrix in power flow Jacobian for power system analysis

Properties of the active power/angle sub-matrix in the power flow Jacobian for power system analysis are studied. The sub-matrix is a dominant and irreducible matrix under very general conditions of power systems, so that it is invertible. Also the necessary conditions for its singularity are given. These theoretical results can be used to clarify the ambiguous understanding of the sub-matrix in current literature, and also provide the theoretical foundations for the applications based on reduced power flow Jacobian. Numerical simulation on the IEEE 118-bus power system is used to illustrate our results.     

PSCAD based multi-infeed HVDC system simulation validated by a recorded fault

More and more high voltage direct current （HVDC） converters are being located in a load area in the Yangtze River Delta Region in China. It＇s large transmission capacity and intensive placement are hardly seen in other countries. Accurate and reliable study tools and methods are extremely needed for power system engineers and researchers to deal with such problems which were never met before and otherwhere. A novel approach on electromagnetic modeling of alternating current / direct current （AC/DC） system is proposed and simulation is carried out to replay a real AC 3-phase to ground fault on a multi-infeed high voltage direct current （MIHVDC） system. AC system is specially simplified. Dynamic models and real parameters are adopted in main AC/DC equipments concerned and retained. Modeling and simulation are based on the power system computer aided design/electro-magnetic transient in direct current （PSCAD/EMTDC） system software package. Comparisons between simulation results and the records from the fault recorders are studied including both AC and DC quantities.     

浅析某车型ESC结构原理及低电压报警故障诊断

近年来,随着人们生活水平的不断提高,汽车越来越多的进入普通百姓家庭,成为大众家庭标配的代步工具。与此同时,对于普通的家庭使用,车辆本身的安全性能在车辆的各项指标中越来越引起人们的重视。车身电子稳定控制系统(Electronic Stability Controller简称ESC)作为主动安全技术的代表,被越来越多国家作为新车上市的强制化标准配置;我国的大众汽车主流,也在不断的增加此配置和卖点。文章将结合某车型的ESC系统结构原理,及ESC系统所存在的一种低电压故障现象分析探讨,以促进对该安全防护系统(ESC)的进一步了解。