70220082 (Transient Analysis of AC Machine Systems)

Course Name: Transient Analysis of AC Machine Systems

Course Number: 70220082

Program: Graduate program

Type: Elective

Credits: 2

Term Offered: Fall

Prerequisites: Electrical Machinery, Principles of Electric Circuits, Numerical Analysis

Instructor(s): Yuguang Sun


Jingde Gao, Xiangheng Wang, and Fahai Li, Analysis of AC Machines and Their Systems (2nd edition), Tsinghua University Press, 2005 (in Chinese).


Jingde Gao, Linzheng Zhang, and Xiangheng Wang, AC Machine Systems, Tsinghua University Press and Springer, 2009.

Jingde Gao and Linzheng Zhang, Fundamental Theroy and Analysis Methods of Transients in Electric Machines, Science Press, 1982 (in Chinese).

Zhang Gaifan, Ma Weiming, Transient Analysis of Synchronous Machines, Hubei Science and Technology Press, 2001.

Course Description:

‘Transient Analysis of AC Machine Systems’ is a course for postgraduates in the fields of electric machines and control, power electronic technique and power system automation.Taking electric machine as the basis, the course thoroughly analyzes composite systems of electric machine and other devices. A series of important problems is covered by the course, including variable speed drive system of AC machines with power electronics and control devices, power energy system composed of AC machines and power transmission lines, as well as electric machine system consisting of AC machines and excitation control devices.For AC machines, a new analysis method named Multi-Loop Method is introduced with its applications fully explained. The method takes account in more affecting factors and is suitable for solving many difficult problems where classical methods often fail.Recent research achievements on the topic are also presented in the course.

Course Objectives and Outcomes:

 Numbers in brackets are linked to department educational outcomes.

1.Students could grasp the fundamental principle of Multi-Loop Method and analyze the electromagnetic relations of AC machines based on single coil, including listing the equations of flux-linkage and voltage, calculating the inductances of single coil and loop composed of these single coils. [1, 5, 11]

2.Students could master the method to analyze AC machines on the basis of one phase winding and corresponding magnetic field on condition that the armature winding is symmetrical, including calculating the inductances for armature phase winding in salient-pole synchronous machines and knowing the periodicity of these inductances. [1, 5, 11]

3.Students could grasp the physical concept of ideal machine pattern and learn to research on the operating conditions of synchronous machines with Park’s formulas and Equivalent Circuits in d,q,0 Axes. [1, 5, 11]

4.Students could master the common reference axes systems including a,b,0 Axes, 1,2,0 Axes, dc,qc,0 Axes, F,B,0 Axes and Fc,Bc,0 Axes, know the transformation relations between them and a,b,c as well as d,q,0 Axes, grasp the features and applications of each reference axes systems. [1, 5, 9, 11]

5.Students could choose suitable reference axes systems to analyze the following special operation modes of synchronous machines: 3-phase sudden short circuit, 2-phase sudden short circuit (including the steady-state), and operation with rectified load. [1, 5]

6.Students could learn every current components in stator and rotor during the transient process after three phases of a synchronous machine are suddenly short-circuited, including their physical concept and time constants at which they decay. Students could grasp the transient parameters related to 3-phase sudden short circuit, and figure out practicable method to identify these transient parameters from the transient experimental current waveforms. [1, 2, 5,11]

7.Students could learn every current components in stator and rotor during the transient process after two phases of a synchronous machine are suddenly short-circuited, including their physical concept and time constants at which they decay. [1, 5,11]

Course Topics:

1. Introduction including the History, Coverage and Methodologies of the course

2. Basic Principles and Mathematical Model (Equations of Loop Voltage and Flux-Linkage) of Multi-Loop Method, Air-Gap Permeance Coefficient of Electric machines, Inductances of Stator Loops Calculated based on Single Coil

3. Inductances of Rotor Loops, Mutual Inductances between Stator Loops and Rotor Loops

4. Influence of Saturation on Parameters, Inductances Produced by Leakage Magnetic Field, Rotor Motion Equation of AC Machines including Calculation of Electromagnetic Torque

5. an Application Example of Multi-Loop Method¾Performances Analysis of Single Phase Asynchronous Motors

6. Basic Electromagnetic Relations of Synchronous Machines with Normal Windings and Structure in a,b,c Axes, Inductances for Armature Phase Winding

7. d,q,0 Coordinate Conversion of Synchronous Machines, Park’s formulas in Actual Values

8. Per-Unit System in Synchronous Machines

9. Physical Pattern of 3-phase AC Machine after Axis Conversion, Equivalent Circuits and Operational Reactances of Synchronous Machines, Output Power and Electromagnetic Torque in Synchronous Machines, Heaviside’s Operational Calculus

10. 3-phase Sudden Short Circuit and Transient Parameters of Synchronous Machines

11. Transformation of Reference Axes Systems and Their Formulas in synchronous machines

12. 2-phase Steady-State Short Circuit of Synchronous Machines

13. 2-phase Sudden Short Circuit of Synchronous Machines

14. Analysis of System of Synchronous Machine and Rectified Load


Experiment(s): 3-phase Sudden Short Circuit Experiment of Synchronous Machines.

lLearn to use Digital Oscilloscope to store waveforms of transient currents and voltages

lMaster the operations to apply sudden short circuit experiment of synchronous machines

lFigure out a practicable method to identify transient parameters of synchronous machines from transient current waveforms during 3-phase sudden short circuit experiment


Course Assessment:

Open-Book Written Examination plus Individual Oral Examination