倪以信动态电力系统PowerSystemDynamics
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--- Of all the complex phenomena on power systems, power system stability is the most intricate to understand and challenging to analyze. Electric power systems of the 21 century will present an even more formidable challenge as they are forced to operate closer to their stability limit.
Introduction (5)
0.4 Definitions of different types of P. S. stability
P. S. stability: the property of a P. S. that enable it to remain in a state of operating equilibrium under normal operating conditions and to return to an acceptable state of equilibrium after being disturbed.
Part I Power system element models
Chapter 1 Synchronous machine models
(a)
Chapter 1 Synchronous machine (S. M.) models
1.1 Ideal S. M. and its model in abc coordinates 1.1.1 Ideal S. M. definition Note:
The time span considered:
transient stability: 0 to 10 seconds mid-term stability: 10 seconds to a few minutes long-term stability(dynamics): a few minutes to 1 hour
0.3 Complexity of modern P. S.
Large scale, Hierarchical and distributed structure, Non-storable electric energy, Fluctuate and random loads, Highly nonlinear dynamic behavior, Unforeseen emergencies, Fast transients which may lead to system collapse in
Power System Dynamics
-- Postgraduate Course of Tsinghua Univ. Graduate School at Shenzhen
NI Yixin
Associate Professor Dept. of EEE, HKU <yxni@eee.hku.hk>
Introduction (7)
0.5 Computer-aid P. S. stability analysis
Introduction (8)
0.6 Contents of the course
Introduction Part I: Power system element models
1. Synchronous machine models 2. Excitation system models 3. Prime mover and speed governor models 4. Load models 5. Transmission line and transformer models Part II: Power system dynamics: theory and analysis 6. Transient stability and time simulation 7. Steady-state stability and eigenvalue analysis 8. Low-frequency oscillation and control 9. *Voltage stability 10. *Subsynchronous oscillation 11. Improvement of system stability Summary
Introduction (6)
0.4 Definitions of different types of P. S. stability (cont.)
Classification of stability (cont.) Based on physical nature of stability: Synchronous operation (or angle) stability: insufficient synchronizing torque -- nonoscillatory instability insufficient damping torque -- oscillatory instability Voltage stability: insufficient reactive power and voltage controllability Subsynchronous oscillation (SSO) stability insufficient damping torque in SSO
Classification of stability Based on size of disturbance:
large disturbance stability ( transient stability, IEEE): nonlinear system models
small disturbance/signal stability ( steady-state stability, IEEE): linearized system models
* S. M. is a rotating magnetic element with complex dynamic behavior. It is the heart of P. S. It
* It provides active and reactive power to loads and has strong power, frequency and voltage regulation/control capability .
Power electronics applications: provides flexible controller in power systems. ( e. g. HVDC transmission systems, STATCOM, UPFC, TCSC, etc.)
Introduction (3)
Introduction (4)
Some viewpoints of Dr. Kundur (author of the ref. book ):
--- The complexity of power systems is continually increasing because of the growth in interconnections and use of new technologies. At the same time, financial and regulatory constrains have forced utilities to operate the systems nearly at stability limits.
Introduction (2)
0.2 Recent trends of P. S.
Systems interconnection: to obtain more benefits. It may lead to new stability issues ( e.g. low-frequency power oscillation on the tie lines; SSR caused by seriescompensated lines etc. ).
Introduction
0.1 Requirements of modern power systems (P. S. ) 0.2 Recent trends of P. S. 0.3 Complexity of modern P. S. 0.4 Definitions of different types of P. S. stability 0.5 Computer-aid P. S. stability analysis 0.6 Contents of our course
* To study S. M., mathematic models are developed for S. M. * Special assumptions are made to simplify the modeling.
Systems are often heavily loaded and very stressed. System stability under disturbances is of great concern.
New technology applications in power systems. (e.g. computer/ modern control theory/ optimization theory/ IT/ AI tech. etc. )
Introduction (1)
0.1 Requirements of modern power systems (P. S. ) Satisfying load demands (as a power source) Good quality: voltage magnitude, symmetric three phase voltages, low harmonics, standard frequency etc. (as a 3phase ac voltage source) Economic operation Secure and reliable operation with flexible controllability Loss of any one element wilபைடு நூலகம் not cause any operation limit violations (voltage, current, power, frequency, etc. ) and all demands are still satisfied. For a set of specific large disturbances, the system will keep stable after disturbances. Good energy management systems (EMS)
seconds or minutes, Complicated control and their coordination requests. -- Modern P. S. is much more complicated than ever and in
the meantime it plays a significant role in modern society.
Introduction (5)
0.4 Definitions of different types of P. S. stability
P. S. stability: the property of a P. S. that enable it to remain in a state of operating equilibrium under normal operating conditions and to return to an acceptable state of equilibrium after being disturbed.
Part I Power system element models
Chapter 1 Synchronous machine models
(a)
Chapter 1 Synchronous machine (S. M.) models
1.1 Ideal S. M. and its model in abc coordinates 1.1.1 Ideal S. M. definition Note:
The time span considered:
transient stability: 0 to 10 seconds mid-term stability: 10 seconds to a few minutes long-term stability(dynamics): a few minutes to 1 hour
0.3 Complexity of modern P. S.
Large scale, Hierarchical and distributed structure, Non-storable electric energy, Fluctuate and random loads, Highly nonlinear dynamic behavior, Unforeseen emergencies, Fast transients which may lead to system collapse in
Power System Dynamics
-- Postgraduate Course of Tsinghua Univ. Graduate School at Shenzhen
NI Yixin
Associate Professor Dept. of EEE, HKU <yxni@eee.hku.hk>
Introduction (7)
0.5 Computer-aid P. S. stability analysis
Introduction (8)
0.6 Contents of the course
Introduction Part I: Power system element models
1. Synchronous machine models 2. Excitation system models 3. Prime mover and speed governor models 4. Load models 5. Transmission line and transformer models Part II: Power system dynamics: theory and analysis 6. Transient stability and time simulation 7. Steady-state stability and eigenvalue analysis 8. Low-frequency oscillation and control 9. *Voltage stability 10. *Subsynchronous oscillation 11. Improvement of system stability Summary
Introduction (6)
0.4 Definitions of different types of P. S. stability (cont.)
Classification of stability (cont.) Based on physical nature of stability: Synchronous operation (or angle) stability: insufficient synchronizing torque -- nonoscillatory instability insufficient damping torque -- oscillatory instability Voltage stability: insufficient reactive power and voltage controllability Subsynchronous oscillation (SSO) stability insufficient damping torque in SSO
Classification of stability Based on size of disturbance:
large disturbance stability ( transient stability, IEEE): nonlinear system models
small disturbance/signal stability ( steady-state stability, IEEE): linearized system models
* S. M. is a rotating magnetic element with complex dynamic behavior. It is the heart of P. S. It
* It provides active and reactive power to loads and has strong power, frequency and voltage regulation/control capability .
Power electronics applications: provides flexible controller in power systems. ( e. g. HVDC transmission systems, STATCOM, UPFC, TCSC, etc.)
Introduction (3)
Introduction (4)
Some viewpoints of Dr. Kundur (author of the ref. book ):
--- The complexity of power systems is continually increasing because of the growth in interconnections and use of new technologies. At the same time, financial and regulatory constrains have forced utilities to operate the systems nearly at stability limits.
Introduction (2)
0.2 Recent trends of P. S.
Systems interconnection: to obtain more benefits. It may lead to new stability issues ( e.g. low-frequency power oscillation on the tie lines; SSR caused by seriescompensated lines etc. ).
Introduction
0.1 Requirements of modern power systems (P. S. ) 0.2 Recent trends of P. S. 0.3 Complexity of modern P. S. 0.4 Definitions of different types of P. S. stability 0.5 Computer-aid P. S. stability analysis 0.6 Contents of our course
* To study S. M., mathematic models are developed for S. M. * Special assumptions are made to simplify the modeling.
Systems are often heavily loaded and very stressed. System stability under disturbances is of great concern.
New technology applications in power systems. (e.g. computer/ modern control theory/ optimization theory/ IT/ AI tech. etc. )
Introduction (1)
0.1 Requirements of modern power systems (P. S. ) Satisfying load demands (as a power source) Good quality: voltage magnitude, symmetric three phase voltages, low harmonics, standard frequency etc. (as a 3phase ac voltage source) Economic operation Secure and reliable operation with flexible controllability Loss of any one element wilபைடு நூலகம் not cause any operation limit violations (voltage, current, power, frequency, etc. ) and all demands are still satisfied. For a set of specific large disturbances, the system will keep stable after disturbances. Good energy management systems (EMS)
seconds or minutes, Complicated control and their coordination requests. -- Modern P. S. is much more complicated than ever and in
the meantime it plays a significant role in modern society.