Stabilization of inter-area and/or oscillatory modes in large-scale power system by voltage impedance power system (VIPS) apparatus based on decentralized control scheme

New technologies such as power electronics have made it possible to change continuously the impedance of a power system not only to control power flow but also to enhance stability. A power system incorporating a variable impedance apparatus such as a variable series capacitor (VSrC) and high-speed phase shifter (HSPS) is called VIPS (Variable Impedance Power System) by the authors. This paper proposes a novel control method of VIPS apparatus such as VSrC and HSPS installed at an interconnecting point for stabilizing inter-area unstable and/or oscillatory modes. The proposed design method of the control system is a kind of hierarchical decentralized control method of a large-scale power system based on a Lyapunov function. Under the proposed control scheme, each subsystem can be stabilized independently by local controllers such as AVR, speed governor and PSS, and then the whole interconnected system can be stabilized by VIPS apparatus taking into account interactions between subsystems. The effectiveness and robustness of the VIPS apparatus control are shown by numerical examples with model systems including a large-scale power system.     

试谈配料方案与质量预测的优化

主要探讨了以理论推算为主，根据物料成分建立不同配比方案，再以实践累积经验为辅组建系统配料方案。此系统方案的建立，克服了烧结原料品种变换频繁带来的质量波动，稳定了混匀料和烧结矿的化学成分。     

西门子V94.3A燃机参数偏离对机组功率和效率的影响

应用小偏差原理，求得燃气轮机机组中10个主要参数(Ck，T1，ηk,ηT,ηc,εk,ξ1,ξ2,ξ3)变化对机组出力和效率的影响系数，并以西门子V94.3A燃机为实例进行讨论。     

厚度控制技术在中厚板轧制生产中的应用

本文探讨了影响中厚板厚度波动的因素，结合安钢中板厂2800mm轧机按合同轧制一批交货重量不大于理论重量船板的生产实践，总结了实际生产中实现高精度厚度控制的有效方法。     

Steady-state torque control system with secondary-current feedback for three-phase squirrel-cage induction motors

This paper presents a highly stable steady-state torque control system with a feedback of a secondary current signal. The torque control system is constructed with a feedback of the secondary current (I₂) signal using a quick response magnetic-field sensor constructed with an amorphous core multivibrator bridge, which can solve the secondary resistance change problem for temperature variation in the IM. Moreover, we added a state feedback to the system to improve the response speed for the unit step function of a torque order. The I₂ sensor method has advantages especially at a low-speed range, in which conventional method using an integrator shows control errors.     

带钢跑偏控制用电液伺服阀的修理与调试

本文介绍了带钢跑偏控制系统中电液伺服阀在使用中常见的几种故障，并针对每种故障产生的原因，具体介绍其修理和调试的方法     

酒泉盆地青西油田快速钻井技术

酒泉盆地青西地区油层储藏深 ,地层可钻性差 ,钻井过程中存在机械钻速低、井斜不易控制、刺断钻具频繁等问题。为此 ,在近年的钻井实践中 ,采取了优化钻具组合、优选钻头、应用 PDC钻头、强化钻具管理等措施 ,使该区块的钻井速度不断提高 ,钻井周期缩短 ,钻头用量减少 ,从而形成了一套适合该区块的快速钻井技术。     

凝析气藏物质平衡方程的改进与应用

为了提高凝析气藏油气采收率，通常采用目前最有效的循环注气保持地层压力的开采方式。在此开采方式下，直接采用气藏物质平衡方程进行地质储量计算将出现很大偏差。针对这种情况，将气藏物质平衡方程进行了改进，得到凝析气藏在注气开发方式下的物质平衡方程。     

Thermophysical Properties of Binary Mixtures of Methyl Methacrylate+Di-Ethers (Ethyl, Isopropyl, and Butyl) at 298.15 and 308.15 K

Experimental data for the densities, dynamic viscosities, sound speeds, and relative permittivities and for three binary systems of methyl methacrylate (MMA)+di-ethers (ethyl, isopropyl, and butyl) at 298.15 and 308.15 K and at atmospheric pressure are reported. The mixture viscosities are correlated by Grunberg–Nissan, McAllister, and Auslander equations over the complete composition range. The sound speeds for the mixtures are also calculated by using free length and collision factor theories, and Nomoto and Junjie equations. From the measured primary properties, deviation functions such as deviations in viscosities, sound speeds, relative permittivities, molar polarizations, excess isentropic compressibilities, and molar electrical susceptibilities were calculated, and the compositional dependence of each of the functions was expressed with a Redlich–Kister type equation. The variation of the Kirkwood correlation factor was determined over the complete composition range.