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动态电力系统

动态电力系统. 张 毅 威 ywzhang@mail.eea.tsinghua.edu.cn 西主楼 III-210 电话 62794698 Ftp ： 166.111.60.30. Chap. 7 Power System Loads. Problem: Why Load modeling is always based on a considerable amount of simplification?. 7.1 Basic Load-Modeling Concepts. Problem:

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动态电力系统

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  1. 动态电力系统 张 毅 威ywzhang@mail.eea.tsinghua.edu.cn 西主楼 III-210 电话 62794698 Ftp：166.111.60.30

  2. Chap. 7 Power System Loads • Problem: • Why Load modeling is always based on a considerable amount of simplification?

  3. 7.1 Basic Load-Modeling Concepts • Problem: • What is the concept of composite load? • Loads are usually represented at what system level? for angular stability or for voltage stability)

  4. 7.1.1 Static load models • 幂次式负荷模型： • 当幂为0，1，2时的特殊性 • For composite system loads, exponent of active load: 0.5-1.8 reactive load: 1.5-6, 1. it varies as a nonlinear function of voltage 2. at higher voltage, ?? Problem: In the absence of specific information, what is the most accepted static load model ?

  5. 多项式负荷模型: ZIP model • How to take into account of the frequency dependency of load characteristics? • What are the typical parameter for Kpf (0,3.0) and Kqf (-2.0, 0) ? • How to get the variation of a bus frequency in simulation? • How to make comprehensive static model? • Is the static load realistic at low voltage? What practice is applied to deal with this problem?

  6. 7.1.2 Dynamic Load Models • Problem: • Why dynamic load model is needed ? • When static and dynamic load models are used ? • What kinds of dynamic loads there are ? (a).(b).(c).(d)

  7. 7.2 Modeling of induction Motors

  8. 7.3 Synchronous Motor Model

  9. 7.4.1 measurement-based approach • steady-state load-voltage characteristics • Problem : At what voltage level? How to get voltage change? What parameters are interested • steady-state load-frequency characteristics • Problem : How to get frequency change? How to separate the influence of voltage change?

  10. Dynamic load-voltage characteristics • What is the basic approach ?

  11. 7.4.2 Component-based approach Base on a structure: Bus load Load class mix Load components Component characteristics

  12. Chap.8 Excitation System • Problem: • What is its basic function? • What is its main control function?

  13. 8.1Excitation sys. requirements • Generator considerations • Basic function : continuous capability • Emergency function: short-term capability • Power system considerations Functions : • voltage control • Transient stability control • Small-signal control

  14. Excitation requirements • Meet response criteria • Provide limiting and protective functions • Meet specific requirement for operation flexibility • Meet the desired reliability and availability

  15. 8.2 Elements of Excitation Sys. • Exciter: provide DC power • Regulator: process and amplify input signal • Terminal voltage transducer and load compensation: • PSS • Limiter and protective circuits:

  16. 8.3 Types • Broad types of excitation system • DC • AC • Static

  17. 8.4.1 Dynamic Performance Measures • Ceiling voltage • Ceiling current • Voltage time response • …

  18. 8.4.2 Small-signal performance Measures • Time response • Frequency response

  19. 8.5 Control and protective functions • 8.5.1 Regurators • 8.5.2 Stabilizing Circuits • 8.5.3 PSS • 8.5.4 Load compensation • 8.5.5 Under-excitation limiter • 8.5.6 Over-excitation limiter • 8.5.7 Volts-per-Herts Limiter and protection • 8.5.8 Field-shorting Circuits

  20. 8.6 Modeling of Excitation Systems • 8.6.1 Per unit system • 8.6.2 Modeling of components • 8.6.3 Modeling of complete excitation system • 8.6.4 Field Testing

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