基于电压源型换流器的多端直流输电电网是解决可再生能源并网和消纳的有效途径,因此研究交直流混合电网的潮流算法很有必要。提出了一种基于扩展节点法的交直流混合电网统一潮流算法。首先建立了电压源型换流站的稳态模型和控制策略及基于扩展节点法的交流和直流电网的网络模型。然后推导了基于牛顿法的统一潮流算法,将交直流混合电网的节点注入电流、支路电流和节点电压作为未知变量同时求解。通过IEEE 30节点交直流混合电网算例验证了所提算法的有效性。

Acoustic signal acquired by polluted insulator discharge on-line monitoring system is easy to be interfered by background noises;thus it is hard to detect feeble discharge pulses in preliminary stage of contamination discharge.In order to solve this problem,mathematical morphology filter and its application to denoising of polluted insulator discharge acoustic emission signal are studied.We analyze the methods of extracting feeble discharge pulses under background noises from the standpoint of integrity,edge detection and Top-Hat transform are combined to process polluted acoustic emission signal.Research results show that this method mentioned above is able to remove noises while preserving important features of polluted insulator discharge acoustic signal with high instantaneity,so it is extremely suitable for on-ling monitoring.

According to the sparse characteristic of the correction equations of large-scale power system,this paper ultilized Krylov subspace theory and designed an inexact Newton method based on flexible precondition and Broyden correction technique.The choosen preconditioner was gradually corrected during the iteration procedure of restared GMRES algorithm,approching the inverse matrix of Jacobian and modifying the convergency of preconditioned method before.Different preconditoners were compared in IEEE 118-and IEEE 300-bus power systems;and the numerical result shows that,comparing with other precondition method,flexible precondition and Broyden correction method enjoys much better adaptability and convergency characteristic,which would benefit the speed of power flow calculation.

A method of constructing of a fiber Bragg grating（FBG） sensor network is described.The technique of online temperature monitoring system of bus line contactors in the gas insulated switchgear（GIS） using the FBG sensor network is also described.The scheme of system designing,implementation method,hardware and software design of the FBG demodulator are expounded especially.At the same time,the functions of the host computer,technique of communication between host and slaves are also described.

运用比较法解析有关能量变化方面的问题,对同学们理解概念和进行简单计算将有所帮助. 一、比较物质的稳定性的强弱 例1 科学家盖斯曾提出:"不管化学过程是一步完成或分几步完成,这个总过程的热效应是相同的."利用盖斯定律可测某些特别反应的热效应.(1)P4(s,白磷)+5O2(g)=P4O10(s);△H1=-2983.2 kJ·mol-1.(2)P(s,红磷)+5/4O2(g)=1/4P4O10(s);△H2=-738.5 kJ·mol-1.