【正文】 rator is monly controlled so that the active power injected into the bus and the voltage at the generator terminals are kept constant. This will be elaborated later when formulating the load flow power from the generator is determined by the turbine control and must of course be within the capability of the turbine generator is primarily determined by there active power injection into the node,and since the generator must operate within its reactive capability curve it is not possible to control the voltage outside certain active capability of a generator depends on a number of quantities, such as active power,bus voltage and other operating conditions, and a typical example is shown in shape of the generator capability curve is specific for each generator and depends on design characteristics,type of generator,hydro or steam turbine,stability constraints, it is also indicated what imposes the different limits for this particular are briefly discussed below. These limits are also discussed in Chapter9.. Model of a load connected to bus k.. Model of a generator connected to bus k. Stator Current Heating Limit The losses in the armature windings are given by ,with obvious losses result in a temperature rise in the armature windings,and this must be limited to a given value other wise the generator is damaged or its lifetime is the plex power is given by it means that for a given terminal voltage, Ut,circles in the PQplane with centre at the origin correspond to constant value of the magnitude of the armature current stator current limit for a given terminal voltage is thus a circle with the centre at the high loading of the generator,this is usually determining there active capability of the synchronous machine.. Reactive capability curve of a turbo generator. Current Heating Limit There active power that can be generated at low load is determined by the field current heating can be shown that the locus for constant field current is a circle with the centre on the Qaxis at ?,where Et is the terminal voltage and Xs is the synchronous radius is given by machine parameter sand typical behaviour is shown in field current heating is usually limiting at over excited operation at low load. End Region Heating Limit When the synchronous machine is underexcited the armature end leakage flux is flux enters and leaves in a direction perpendicular to the stator laminations causing eddy currents in the laminations,and hence can limit the capability,particularly for round rotor typical example of such a limitation is shown in .The limits on reactive power generation and absorption given in this subsection and the two previous ones are imposed by internal synchronous machine seen they are dependent on the terminal voltage of the are also other considerations that can further limit the reactive capability of the synchronous are stability limits that could further limit the operation of the machine in underexcited operation.電力系統(tǒng)建模與分析功率流分析故障分析電力系統(tǒng)動(dòng)態(tài)穩(wěn)定第一部分 靜態(tài)分析第一章 引言 本章給出了原因：為什么一個(gè)代數(shù)模型可用于電力系統(tǒng)穩(wěn)定狀態(tài)的描述。., they are not is how ever possible to develop unified plex expressions which can be used for lines,transformers,and phaseshifters, regardless of the side on which the tap is located(or even in the case when there are taps on both sides of the device).Consider initially the model in in which shunt elements have been temporarily ignored and and 。外文原文及中文翻譯Modelling and Analysis of Electric Power SystemsPower Flow Analysis Fault AnalysisPower Systems Dynamics and StabilityPreface In the lectures three main topics are covered,.? Power flow an analysis? Fault current calculations? Power systems dynamics and stability In Part I of these notes the two first items are covered,while Part II givesAn introduction to dynamics and stability in power systems. In appendices brief overviews of phaseshifting transformers and power system protections are given. The notes start with a derivation and discussion of the models of the most mon power system ponents to be used in the power flow derivation of the power ?ow equations based on physical considerations is then resulting nonlinear equations are for realistic power systems of very large dimension and they have to be solved most monly used techniques for solving these equations are role of power flow analysis in power system planning,operation,and analysis is discussed. The next topic covered in these lecture notes is fault current calculations in power systematic approach to calculate fault currents in meshed,large power systems will be needed models will be given and the assumptions made when formulating these models will be demonstrated that algebraic models can be used to calculate the dimensioning fault currents in a power system,and the mathematical analysis has similarities with the power ?ow analysis,soitis natural to put these two items in Part I of the notes. In Part II the dynamic behaviour of the power system during and after disturbances(faults) will be concept of power system stability is de?ned,and different types of power system in stabilities are the phenomena in Part I could be studied by algebraic equations,the description of the power system dynamics requires models based on differential equations. These lecture notes provide only a basic introduction to the topics facilitate for readers who want to get a deeper knowledge of and insight into these problems,bibliographies are given in the text.Part IStatic Analysis1 IntroductionThis chapter gives a motivation why an algebraic model can be used to de scribe the power system in steady is also mot