The Energy Flow Approach for Oscillation Source Location and Damping Evaluation

Transcription

1 1 The Energy Flow Approach for Oscillation Source Location an Damping Evaluation Lei CHEN PhD, Associate Professor Department of Electrical Engineering Tsinghua University

2 Backgroun What is oscillation source? cause of oscillation Disturbance source in force oscillation Generator with negative amping (often cause by wrong parameters) in free/natural oscillation Why shoul we fin oscillation source? Online location of oscillation source is the key to effective measures for oscillation suppression Remove the isturbance source or ajust the negatively ampe generator

3 3 Energy Base Iea The concept of energy is wiely use in oscillation or vibration analysis Oscillations are accompanie by the conversion of energy Kinetic energy, potential energy The amount of energy is consistent with the oscillation amplitue More energy, larger oscillation amplitue The issipation of energy brings amping effect Friction The component proucing energy is the oscillation source, which maintains or increases the oscillation amplitue

4 4 Concept of Energy Flow Energy in power system ynamics: Transient energy The construction of energy function is very ifficult Not suitable for online application with measurements Energy flow Compute with measurements, inepenent of energy functions The energy issipation or prouction can be ientifie with the energy flow on the network

5 5 Energy Flow Computation The energy flowing from bus i to branch L ij is [1] W ( I U I U ) ij ij, x i, y ij, y i, x Q ij ( P U ) ( P f t Q (ln U )) ij i i ij i ij i U i Compute with WAMS ata an inepenent of energy functions Ientical to the transient energy The energy flow into an element is compose of two types of terms: conservative term (inepenent of integral path) - transient energy non-conservative term (epenent of integral path) - energy issipation * 1 Im I V T P D t G i i J 0 m 0 x x 0 [1] Lei Chen, Yong Min, Wei Hu. An energy-base metho for location of power system oscillation source. IEEE Trans Power Syst, 013, 8():

6 6 Conservative an Non-Conservative Terms conservative term - transient energy - oscillating non-conservative term - energy issipation monotonically changing (rising or escening) * 1 Im I V T P D t G i i J 0 m 0 x x 0

7 7 Energy Dissipation or Prouction The energy issipation/prouction can be extracte from the energy flow, which reflects the amping of a component in low frequency oscillation Net Energy Flow / Dissipating Energy Flow D W P Q ln U ij ij i ij i P f t Q ln U ij i ij i Compute with eviations Reserve non-conservative terms but eliminate conservative terms Energy flow into a generator that issipates transient energy an has positive amping

8 8 Energy Dissipation Correspons to Positive Damping Energy issipation is consistent with amping torque of a generator Mathematically prove: in Heffron-Phillips moel, actual energy issipation in a perio equals the energy issipate by the amping torque T t t 0 ( E ) t K t q D 0 X X t Damping torque can be evaluate with energy issipation t Test results

9 9 Energy Dissipation in Detaile Generator Moel Generator with a fiel wining an 3 amper winings J m e q 1 q 1 q q q q 0 T P P D U R I f f f f R R R I I I Conservative terms 1 P T m J 0 ff 11 a 1 1 q q a q 1 X ( X X X ) ( X ) I X X X a 11 ff a ff 11 a 1 X X 1 1 f ff 1 ( X ) a f 1 X X X 1 X ( X X X ) ( X q ) I X X X a q 1 1 q q a q 1 1 q q a q 1 X X q 1 q 1 1 q q ( X ) a q 1q q X X X Non-conservative terms W D D q 1 q 1 q q q q 0 t W ( U I I R ) t f f f f f W I R t W I R t W I R t q Energy issipations of winings : amping [] Energy issipation coefficients as Pm changes [] Lei Chen, Fei Xu, Yong Min, Fang Li. Evaluation of amping of winings in a generator using oscillation energy issipation. 014IEEE Power & Energy Society General Meeting, 7-31July 014, National Harbor, Marylan, USA.

10 Energy Prouction of Disturbance Source in Force Oscillation The isturbance source in force oscillation prouces 10 Perioic isturbance on mechanical power P P P s in t m m Energy prouction of isturbance P s in t t 0 Perioic isturbance on fiel voltage E E E s in t f f Energy prouction of isturbance X 1 X E sin t E t q

11 11 Online Oscillation Source Location PMU/WAMS base Use ata: P, Q, U, f Steps When the oscillation is etecte, compute the energy flow in the network using a short perio (often less than 10s) of D ata with W P f t Q ln U ij ij i ij i Compute the slope of W ij D using linear fitting, which reflects the power of the energy flow Fin the energy source using the irection an the magnitue of the energy flow power, an it is the oscillation source

12 1 Actual Oscillation Incients Analysis P of line Pingban-Shapo Pingban plant oscillation Hz Cause by the trip of one sening line Pingban-Baise Negatively ampe free oscillation The generators in Pingban are proucing energy Energy flow from Pingban generators to the system

13 13 Actual Oscillation Incients Analysis Three gorges station oscillation - 0.8Hz Cause by wrong PSS parameters in Youer plant Nearly zero ampe free oscillation The Youer plant is proucing energy Energy flow from ifferent plants to the system

14 14 Actual Oscillation Incients Analysis P of line gen #4 Faer plant oscillation Hz Cause by governor fault in gen #4 of Faer plant, which inuces power oscillation of the generator Force oscillation Gen #4 is proucing energy Energy flow from generators to the system

15 15 Online System Implementation Base on PMU/WAMS in China Southern Gri Successfully locate oscillation sources in many incients since its commissioning in 013 Main interface

16 16 Online System Implementation When oscillation etecte

17 17 Online System Implementation When oscillation etecte

18 18 Other Applications Also implemente in Center China Gri Company Successfully use in China Xinjiang an Xizang Gris for oscillation incient analysis Through the energy flow insie the generator, the oscillation source can be further locate at exciter or governor, which is helpful for cause analysis an efect correction Exciter X 1 X E f E q ( E ) 1 q ( X I X qiq ) X X Transient Energy 1 T 0 J X Generator T 0 ( Eq ) X D 0 Energy Dissipation t I U I U q q t P ( ) e Qe U U Power Gri Governor P m P e P e

19 19 Connection with Moal/Eigen Analysis The energy issipation is connecte with amping ratio in moal analysis [3] i K E D C, i σ : real-part of eigenvalue K EDC,i : energy issipation coefficient of generator The amping of the whole system of a moe comes from the total energy issipations of generators [3] Lei Chen, Yong Min, Yiping Chen, et al. Evaluation of generator amping using oscillation energy issipation an the connection with moal analysis. IEEE Trans Power Syst, 014, 9(3):

20 0 Discussions on New Developments Physical meaning of oscillation energy flow Connection with the actual electrical power Application in transient stability The transient energy injection of a fault can be compute through the energy flow at the fault point with the voltages an the currents Energy function is not neee Transient stability may be stuie through the energy flow on the network W I R t W I R t 1 q 1 q 1 q W I R t q q q

21 1 Thanks! Lei CHEN PhD, Associate Professor Department of Electrical Engineering Tsinghua University