Sincrofazori Sen

ASPECTE ESENIALE ALE INTRODUCERII SISTEMULUI DE MSURARE A SINCROFAZORILOR N SISTEMUL

ENERGETIC NAIONAL

SYNCHROPHASOR MEASUREMENT SYSTEM IMPLEMENTATION IN THE NATIONAL POWER SYSTEM ESSENTIAL ASPECTS

Nicolae CHIOSA Nicolae PANTAZI

C.N.T.E.E. Transelectrica S.A., Transmission Branch Timioara Piaa Romanilor nr. 11, Timioara

Tel./fax:+40-0256-294054, E-mail: [email protected]

Bucur LUTREA Ioan BORLEA Constantin BRBULESCU Politehnica University of Timioara, Romania, Electrical Power Engineering Department

Bd. Vasile Prvan, nr. 2, 300433, Timioara Tel./fax+40-256-403416, E-mail: [email protected]

Doru Mircea PUNESCU C.N.T.E.E. Transelectrica S.A., National Power Dispatching Operating Unit

Rezumat. Lucrarea este consacrat prezentrii unor aspecte deimplementare a sistemului de msurare a sincrofazorilor de ten-siune n Sistemul electroenergetic naional (SEN) romnesc. Esteprezentat arhitectura general a sistemului de msur, schemelebloc pentru punctele locale i punctul central de msur, avan-tajele i beneficiile pe care acest sistem de msur le poate aducen conducerea operativ a SEN. Cuvinte cheie: sincrofazori, sistem electroenergetic naional, sistem de poziionare global prin satelit, sistem sincron demsurare a fazorilor

Abstract. This paper tackles various aspects regarding the imple-mentation of voltage synchrophasors in the Romanian National Power System. In what follows, we will establish the general architecture of the measuring system, the flow charts for the local measuring points and for the central measuring point, the advantages and benefits that this particular measuring system mayconvey to the operative control of the National Power System. Keywords: Synchrophasors, National Power System Global Posi-tioning System, Synchrophasors measurement system

1. Introducere Compania Naional de Transport al Energiei Electrice,

C.N.T.E.E. Transelectrica S.A., asigura serviciul de trans-port al energiei electrice, de conducere tehnic a Sistemul-ui Electroenergetic Naional (SEN) i de administrare apieei de energie electric i este membru n Uniunea pentruCoordonarea Transportului Energiei Electrice (UCTE).

Ca urmare a transformrilor prin care trece societatea,aflat n faza de dezvoltare post industrial i a progresuluitiinific i tehnologic continuu, Transelectrica S.A.trebuie s fac fa urmtoarelor provocri: Globalizarea: Transelectrica este parte component a

UCTE asumndu-i responsabilitile ce-i revin pentruteritoriul rii i zona de sud-estic a continentului.

Deregularizarea. Din structura SEN caracteristic anilor 1990, s-au format mai multe Companii, ocupndpoziii precise n lanul energetic. Complicatele relaiicare se stabilesc ntre Companii trebuie reglementatei arbitrate att pe cale juridic ct i cu ajutorul Auto-riti Naionale de Reglementare in domeniul Energiei(ANRE). Un alt aspect al deregularizrii este externa-lizarea din Transelectrica a unor activiti legate de

1. General aspects The National Power Grid Company (C.N.T.E.E. Trans-

electrica S.A.) ensures the power transmission, the techni-cal control of the National Power System and the power market management. It is also a member of the Union for the Co-ordination of Transmission of Electricity (U.C.T.E.).

As a result of all the society changes due to the scien-tific and technological progress, Transelectrica S.A. has to deal with the following challenges: Globalization: Transelectrica is part of the U.C.T.E.

carrying out the responsibilities inherent to the coun-try and to the southeastern area of the continent.

Deregulation: The National Power System structure characteristic from the 1990s has given birth to several Companies, each occupying precise positions in thepower chain. The complicated relations established be-tween the Companies have to be regulated and man-aged judicially as well as with the help of the National Power Regulating Authority (ANRE). Another aspect of the deregulation is the exclusion of certain activities related to equipment maintenance, secondary services from Transelectrica etc.

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mentenana echipamentului, servicii care nu fac obiectulactivitii principale a Companiei etc.

Liberalizarea. Au fost nfiinate i ncep s funcionezestructurile Pieei de energie. n condiiile n care energiatrebuie adus la consumator de acolo de unde ea estemai ieftin, apar congestiile pe linii i problemele legatede reglajul i stabilitatea tensiunii n nodurile sistemuluii de decontarea energiei electrice transportate etc.

Informatizarea: Sistemul SCADA s-a extins mult,ceea ce asigur informaiile primare necesare tuturorcomponentelor Transelectrica: staii electrice, dispece-rate, sucursale de transport. Astfel a fost asigurat supor-tul absolut necesar conducerii operative a SEN i adesfurrii tuturor celorlalte activiti ale Companiei.Avnd n vedere ritmul accelerat de evoluiei al progre-sului tehnic i necesitatea alinierii la standardele inter-naionale, n mod cert activitatea de perfecionare a plat-formei informatice a Companiei va reprezenta i n viitoro preocupare permanent a conducerii Transelectrica. Realizarea unui sistem de msur a sincrofazoriloraparine acestui gen de preocupri.

Eficientizarea: Organizarea Companiei a fost completrestructurat i se continu acest proces prin trecereala sistemul de exploatare centralizat a staiilor i liniilor. S-au externalizat o serie de activiti de mic importan, ceea ce a permis conducerii Companiei s se focalizezeasupra obiectivelor principale ale domeniul specific deactivitate, cu rezultate directe asupra creterii profitului.

Modernizarea: Este numitorul comun al ntregii evoluiidin ultimii ani ai Transelectrica. Modernizarea se des-foar n profunzime, n toate componentele Companiei:concepie, echipamente, proceduri de lucru, organizare,personal. n consecin, Transelectrica trebuie s reacioneze

prompt i s gseasc soluii adecvate n faa solicitrilorprezentate. Una dintre acestea o reprezint realizarea unuisistem de msur pentru sincrofazori. Prezentarea aspecteleeseniale ale implementrii sale formeaz substana prezenteilucrri.

Liberalization: The structures of the Power Market have been established and they are beginning to work. Because the power may be brought from where it is cheaper, congestion on the lines and power supplied payment, adjustment and stabilization voltage prob-lems will occur in the system buses.

Information management: The SCADA system has largely expanded, and this ensures the primary infor-mation necessary to all parts of Transelectrica: power stations, dispatching units, transport branches. This ensures the compulsory support necessary to control both the operation of National Power System and the deployment of all other activities within the Company. Considering the very fast technical progress and the necessity of alignment with the international standards,the development of the computer platform will un-doubtedly remain a continuous interest for Transelec-trica. Developing a measuring system for synchrophasorsis part of these interests.

Efficiency: The structure of the Company has been completely rebuilt and passing to the centralized sta-tion and line exploitation system will continue this process. A series of less important activities have been excluded from Transelectrica. This has allowed the Company staff to focus on the main objectives in its specific line of work, which had direct results on the profit growth.

Modernization: It is the main objective for Transelec-tricas entire evolution in the latest years. The mod-ernization takes place profoundly, affecting each part of the Company: ideas, equipment, work procedures, personnel training and organization. Consequently, Transelectrica must react promptly and

find appropriate solutions to the above stated challenges. Developing a measuring system for synchrophasors is one of them. The fundamental aspects of its implementation are approached in this paper.

2. Concepte de baz referitoare la sincrofazori 2.1. Repere ale evoluiei sincrofazorilor

Pe msur ce Sistemele Electroenergetice (SEE) seextind tot mai mult, comportarea dinamic a sistemuluiridic probleme tot mai numeroase i mai dificile, deveninddin ce n ce mai greu de modelat. n plus, cunoaterea exact,prin msurtori n timp real a mrimilor electrice din SEEi abilitatea de a realiza controlul n tip real al sistemului,asigur o exploatare optimizat i uureaz prevenireaavariilor.

Dei fazorii folosii pentru reprezentarea mrimilor ncurent alternativ au fost foarte clar nelei de peste 100 deani, definiia precis a fazorilor sincronizai n timp (sincro-fazori) a fost introdus mult mai recent de ctre standardeleinternaionale IEEE 1344 i IEEE C37.118, IRIG-B. Acestfapt, nsoit de apariia sistemului GPS i deschiderea luispre aplicaiile comerciale a condus n ultimii ani la rea-lizarea i extinderea foarte rapid a msurrii sincrofazorilorn SEE continentale.

Principalele repere istorice privind evoluia utilizriisincrofazorilor n SEE sunt:

2. Synchrophasors basic aspects 2.1. Landmarks in the evolution of synchrophasors

As the Power Systems develop more and more, the dynamic behavior of the system introduces more and moredifficult problems, becoming harder and harder to simu-late. Furthermore, optimized exploitation and easier fault prevention are ensured through precise knowledge, via real time measuring of the electric quantities in the Power System, and through the ability to accomplish the system real time control.

Although, the phasors used to represent the alternating current quantities have been clearly understood for over 100 years, the precise definition of the synchronized in time phasors (synchrophasors) has been introduced much recently through the international IEEE 1344 and IEEE C37.118, IRIG-B standards. This, in direct relation to the launching of the GPS and its availability in commercial applications, has led, in the latest years, to the fast devel-opment of the measuring methods of synchrophasors in continental Power System.

The main historical landmarks regarding the evolution of synchrophasors use in Power System are:

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1893 C.P. Steinmetz propune tehnici matematice deanaliz a reelelor de curent alternativ cu ajutorul fazo-rilor, care sunt preluate rapid, pe scar larg, fiindunanim acceptate.

1970 Paul Dimo public lucrarea Analiza nodal asistemelor electroenergetice propunnd o metod demonitorizare i control a sistemului bazat pe urmrireafazorilor tensiunilor i curenilor nodali i un echipamentoriginal Anagraful, bazat pe cunoaterea defazajelortensiunilor nodurilor i dedicat supravegherii regimurilornodului respectiv.

1987 Primul GPS operaional sincronizat experimental. 1992 Primul test de msurare a sincrofazorilor aplicat

unei zone mai extinse i validarea modelului folosit. 2004 Prima recomandare oficial pentru utilizarea

dispozitivelor sincronizate n timp.

1893 C.P. Steinmetz suggests mathematical methods of analyzing the alternating current grids through phasorsand they spread widely, being universally validated.

1970 Paul Dimo publishes The nodal analysis of power systems, forwarding a monitoring and control method of the system based on tracking the voltage and nodal current phasors, using a particular equipment the Anagraph, which, through knowledge of the phase shifts of the nodal voltages, monitors the regimes of thatparticular bus.

1987 The first operational GPS experimentally syn-chronized.

1992 The first test of synchrophasor measuring sys-tem was applied to a more extensive area and the vali-dation of the used model has been done.

2004 The first official recommendation regarding the use of time synchronized devices.

2.2. Sistemul GPS Sistemul de poziionare global prin satelii (Global

Positioned Satellite GPS) a fost realizat de SUA iniialn scopuri militare. El const din 24 de satelii plasai n 6orbite la o nlime de aproximativ 16000 km de la suprafaaPmntului (jumtate din altitudinea unei orbite geosin-crone). Poziionarea planului orbital al sateliilor este n aamod realizat nct n orice moment i pentru orice punct depe suprafaa pmntului sunt vizibili cel puin 4 satelii.

Utilizarea civil a sistemului GPS este s transmit coordonatele geografice ale unui receptor staionar, dupce acesta a trimis n prealabil un impuls care a fost recep-ionat de satelit. De asemenea sistemul GPS transmite unimpuls de sincronizare la fiecare secund care poate fiinterpretat de ctre receptorul de pe suprafaa Pmntului.Pentru aplicaiile civile precizia acestui semnal de sincro-nizare este de cel puin 1 microsecund, ceea ce face posibilsincronizarea proceselor i deci i a msurtorilor din oricepunct de pe Pmnt cu o acurate suficient pentru moni-torizarea i controlul fenomenelor din SEE. n Fig.1 esteprezentat schema de principiu a unei instalaii de msursincronizat a fazorilor (sincrofazori).

2.2. The GPS system The Global Positioning System (GPS) has been, ini-

tially, developed in the USA for military purposes only. It consists of 24 satellites positioned in 6 orbits at a distance of 16000 km from the Earths surface (half of the altitude for a geosynchronous orbit). The positioning of the orbital plan of the satellites is designed so that at any given mo-ment and in any point on the Globe there are at least 4 satellites visible.

The civil use of the GPS system is to convey the geo-graphical coordinates of a stationary receiver, which has previously sent an impulse that had been received by the satellite. Moreover, the GPS system sends each second a synchronization impulse that can be read by the receiver on the surface of the Earth. For civilian application, the accuracy of this synchronization signal is at least 1 micro-second. This makes possible the synchronization of proc-esses and therefore of various measurements taking place in any points on the Globe with enough accuracy to moni-tor and to control the phenomena occurring within the Power System. Fig. 1 supplies the basic diagram of a syn-chronized measuring unit of phasors (synchrophasors).

Fig. 1. Diagrama bloc a sistemului de msurare a sincrofazorilor Fig. 1. Synchrophasors measuring system diagram.

Fig. 2. Definirea sincrofazorilor Fig. 2. Related to synchrophasors definition.


2.3. Definiii Fazorul este un vector care are amplitudine, direcie i

sens, fiind reprezentat matematic de un numr complexcaracterizat prin amplitudinea i faz, corespunztoaremrimilor respective ale unei funcii cosinusoidale. Mrimilecosinusoidale reprezentate prin fazori, ntr-o diagramcomun, au aceeai frecven.

Sincronizare este operaia n care fazorii sunt raportai la o origine comun a timpului, de regul stabilit cu ajutorulGPS.

O und alternativ poate fi reprezentat matematicprintr-o ecuaie [1]:

2.3. Definitions The phasor is a vector with amplitude, direction and

orientation. It is mathematically represented by a complex number that accounts for the amplitude and for the phase, in direct relation to the corresponding quantities from a cosine function. In the same diagram, the cosine quantitiesthat are represented by phasors have the same frequency.

The synchronization is the operation through which the phasors receive the same origin of time, usually estab-lished through GPS.

An alternating wave may be mathematically representedthrough an equation [1]:

)cos()( += tXtx m unde: Xm - amplitudinea undei sinusoidale, viteza un-ghiular care depinde de frecven i unghiul iniial alundei. O reprezentare simplificat a ecuaiei de mai sus este:

where: Xm the amplitude of the sinusoidal wave, the angular velocity that depends on the frequency and theprimary angle of the wave. A simplified form of the equa-tion above is:

= mXX Corelarea sincrofazorilor cu valorile efective (RMS) se

poate face folosind factorul de scalare 21 existent ntre valoarea efectiv i amplitudinea fazorului.

Sincrofazorii sunt fazori situai n diferite puncte alespaiului, definii fa de un moment de referin unic ntimp, stabilit folosind GPS (vezi Fig. 2). Desigur, fazaunui sincrofazor trebuie corectat astfel nct ea s incont de ntrzierile cauzate de orice tip de temporizareintrodus n procesul de msurare a lui.

n Fig.2 este marcat referina de timp (UTC Time), rea-lizat cu ajutorul sistemului GPS. La momentul de timp 1,unda are unghiul 1 i amplitudinea X1 (considernd unregim cu frecven constant i amplitudine variabil). Si-milar la momentul de timp 2, unda are unghiul 2 i ampli-tudinea X2 . Trebuie subliniat c standardul referitor lasincrofazori se concentreaz pe semnale staionare careexist atunci cnd forma undei este constant pentru operioada n care se fac msurtorile.

Fazorii nregistrai (msurai) vor avea un marcaj de timppe baza referinei UTC. Marcajul de timp este un mesajformat din: Secunda Secolului (Second of Century - SOC),Fraciunea de secund (Fraction of Second - FOS) i Indicator de calitate al timpului (Time Quality Indicator- TQI). Marcajul SOC precizeaz numrul de secunde care s-au curs din 1 ian. 1970. Marcajul FOS divizeaz secundan 16.777.216 pri sau contorizeaz pri de secund de59,6 ns.

Standardul IEEE C37.118 revizuiete Standardul IEEE1344 i propune s fie standardizate cteva frecvene deraportare i intervale de raportare, referitor la msurareasincrofazorilor.

Msurarea sincrofazorilor trebuie s-i pstreze preciziapentru un domeniul larg de condiii de funcionare a SEE.n acest sens s-a definit un indicator de calitate care apre-ciaz global acurateea de msurare a sincrofazorilor.

Eroarea total (Total vector error - TVE): este rdcinaptrat din suma diferenelor la ptrat dintre prile real(Xr) i imaginar (Xi) a fazorului teoretic actual (X(n)) i fazorul estimat (X) raportat la amplitudinea fazoruluiteoretic:

The correlation of the synchrophasors with the effec-tive values (RMS) may be achieved by using the scale factor of 21 hich connects the effective value and the amplitude of the phasor.

w

The synchrophasors are phasors situated in various points in space, defined with respect to a reference mo-ment that is unique in time and that is established using the GPS (Fig. 2). Certainly, the phase of a synchrophasor must be corrected so that it takes into account the delays generated by its measuring process.

In Fig. 2, we have marked the time reference (UTC Time), established via the GPS system. At the moment of time 1, the wave has the 1 angle and the X1 amplitude (considering a regime of constant frequency and varying amplitude). Similarly, at the moment of time 2, the wave has the 2 angle and the X2 amplitude. We must stress that the standard corresponding to synchrophasors is focused on the stationary signals that exist only when the wave form is constant for a period over which all measurement are carried out.

The recorded (measured) phasors will have a time markbased on the UTC reference. The time mark is a message that consists of: Second of Century (SOC, Fraction of Sec-ond (FOS) and Time Quality Indicator (TQI). The SOC mark assigns the number of seconds that have passed sinceJanuary 1st, 1970. The FOS mark divides the second into 16.777.216 parts or counts divisions of second of 59.6 ns.

The IEEE C37.118 standard reconsiders the IEEE 1344standard and suggests the need to standardize several ref-erence frequencies and intervals, with respect to the measur-ing of the synchrophasors.

The measuring of the synchrophasors must keep its accu-racy for a wide range of operating conditions of the SEE. Forthat reason, a quality indicator has been defined to assess globally the measuring accuracy of the synchrophasors.

The total vector error (TVE) is the square root of the sum of the squared differences of the real part Xr and the imaginary part Xi of the real theoretical phasor X(n) and the estimated phasor X against the amplitude of the theo-retical phasor:


2 2

2 2

( ( ) ) ( ( ) )*100

( )r r i i

r i

X n X X n XTVEX X

+ = +

n cele mai multe cazuri, standardul referitor la msu-rarea sincrofazorilor precizeaz c, eroarea total trebuiemeninut sub 1 % n condiii de maxim 5Hz din frec-vena nominal i maxim 10 % factor de distorsiune ar-monic.

In most cases, the standard established for measuring synchrophasors states that the total error must be kept under1%, observing conditions of max 5 Hz for the rated fre-quency and of max 10% for the waveform distortion factor.

2.4. Diverse probleme legate de utilizarea sincrofazorilorUna din problemele importante privind coordonarea

msurtorilor sincrofazorilor o constituie prezena n reeauacu mai multe niveluri de tensiune, a transformatoarelor cuposibiliti de rotire a fazorului tensiunii prin cifra de cone-xiune sau prin reglaj longo-transversal. n situaia n caren reea exist astfel transformatoare, rezultatele msur-torilor sincrofazorilor trebuie corectate pentru a ine seamade defazajele cauzate de transformatoare.

O alt problem o constituie nelegerea deosebirilorcare exist dintre datele achiziionate de SCADA i dateleoferite de sistemul de achiziie a sincrofazorilor [2]. n acestsens, informaiile din Tabelul 1 sunt pe deplin edificatoarerelevnd superioritatea sincrofazorilor.

2.4. Various synchrophasors application aspects One of the main problems of synchrophasors measur-

ing coordination arises from the existence of the phase shifting transformers in the multiple voltage network lev-els. In such cases, the results of the measuring of the syn-chrophasors must be corrected so that they take into ac-count the phase shifts generated by the transformers.

Another problem resides in understanding the distinc-tions that exist between the data acquired by the SCADA system and the data supplied by the synchrophasor acqui-sition system [2]. Accordingly, the information in Table 1 pertinently reveals the superiority of synchrophasor.

Tabelul 1. Date comparative ale sistemelor de achiziie SCADA i sincrofazori.

Caracteristic SCADA SINCROFAZORI Tipul msurtorii analogic digital

Rezoluie 2 - 4 eantioane / s pn la 60 eantioane / s Observabilitate regim staionar regim dinamic / tranzitoriu Monitorizare local arie larg

Msurarea fazei nu da Mrimea msurat Modul modul i unghi

Sincronizarea datelor precizie 2 4 s precizie 1 s Table 1. Comparative data regarding SCADA and synchrophasors measuring systems

Characteristic SCADA Synchrophasors Measurement type analog digital

Resolution 2 - 4 samples / s up to 60 samples / s Observability steady-state regime dynamic / transitory regime Monitoring local wide area

Phase measurement no yes Measured quantity module module and angle

Data synchronization 2 4 s accuracy 1 s accuracy

3. Cteva aplicaii ale sincrofazorii Valorile sincrofazorilor constituie o informaie extrem

de valoroas datorit principalelor ei caracteristici: completitudine pentru c pe lng valorile tensiunilor

n noduri, sincrofazorii ofer i defazajele existente;n consecin sincrofazorii din nodurile sistemuluicaracterizeaz complet starea sistemului n momentulrespectiv,

coerena se datoreaz sincronizrii msurtorilor cu omare precizie (eroare sub 1 s), ceea ce face posibilanalizarea cu mare acuratee nu numai a regimurilorstaionare sau lente, ci i a celor tranzitorii.

3. Some synchrophasor applications Due to their main characteristics, the values of the syn-

chrophasors provide very important information: completeness because, aside from the values of the

nodal voltages, the synchrophasors also indicate the existing phase shifts; consequently, the synchrophasorsfrom the system nodes fully characterize the state of the system at that given moment

coherency due to the synchronization of the measuring with high accuracy (less than 1 s error), which makes possible to analyze, with high accuracy, not only the steady state or slow regimes, but also the transitory ones.


Din aceste motive, datele sincrofazorilor pot fi exploataten extrem de multe aplicaii [3,4], cele mai importante fiindenumerate n continuare: identificarea unor parametrii ai elementelor de sistem,

ai modelelor matematice ale sistemului; monitorizarea funcionrii i mbtrnirii echipamentelor,

a variaiilor de frecven pe zone ale sistemului, a con-diiilor de schimb de energiei pe magistralele de inter-conexiune, a stabilitii statice la nivel de nod i pe an-samblul sistemului i a oscilaiilor electromecanice;

estimarea strii i analiza regimurilor permanente; reglarea circulaiei puterilor active i gestionarea con-

gestiilor; reglarea tensiunii i circulaiei puterilor reactive; restaurarea strii sistemului n urma unor avarii grave; analiza regimurilor tranzitorii; analiza semnturii evenimentelor.

As a result, the data supplied by synchrophasors may be applied in a large number of applications [3, 4], the most important of which are: identifying various parameters for the elements in the

system and for the simulation model of the system; monitoring the operation and aging of the equipment,

the frequency variations for various areas of the system, the power exchange conditions over the interconnectingbuses, the steady-state stability on a bus level and on the whole system and the electromechanical oscillations;

gauging the state and analyzing the stationary regime; regulating the active powers flow and managing con-

gestion; regulating the voltage and the reactive powers flow; restoring the state of the system subsequent to serious

system failures; analyzing the transitory regimes; analyzing the signature of events.

4. Descrierea soluiei propuse

Sistemul propus [5] pentru msura sincrofazorilor(Fig. 3), este prevzut s achiziioneze date n 12 Staiielectrice de 400 kV ale SEN. Acest lucru implic mon-tarea n fiecare staie a unui echipament de msur, mo-nitorizare i control local (EMMC) de tip PMCU, o unitatecentral de colectare arhivare i vizualizare a msurto-rilor (UCCAV), care se va monta la Unitatea OperaionalDispecer Energetic Naional (UnO-DEN) Bucureti i 5staii de lucru pentru analiz si vizualizare (SLAV) instalaten incinta celor 5 Dispecerate Energetice Teritoriale (DET).Arhitectura sistemului de msur a sincrofazorilor este detip deschis pentru a asigura posibilitatea actualizrii lui cufunciuni (software i hardware) care vor fi dezvoltateulterior.

Stabilirea locaiilor unde vor fi instalate punctele demsur s-a fcut pe baza unui studiu care a luat n consi-derare urmtoarele criterii: instalarea n nodurile problem, pentru a se putea

monitoriza stabilitatea la tensiune a acestora; pe barele de 400 kV din imediata apropiere a centralelor

puternice din sistem, pentru monitorizarea oscilaiilori a problemelor de stabilitate dinamic;

la capetele magistralelor reelei, unde apar frecventcongestii, pentru a se putea urmri nedepirea limiteitermice de ncrcare;

la capetele liniilor de interconexiune cu subsitemelenvecinate, pentru a se putea asigura condiii de obser-vabilitate a fazorilor n ntreg sistemul UCTE i rapor-tarea la o singur referin, unic n UCTE, a tuturorfazorilor;

echipamentele instalate s mbunteasc observabi-litatea estimrii strii ntregului sistem. Cele 12 puncte de msur au fost stabilite de ctre

UnO-DEN i sunt urmtoarele: Gutina, Bucureti-Sud, Roiori, CNE Cernavoda, Isaccea, Porile de fier,Tnreni, Braov, Iernut, Arad, Mintia, Nadab.

Pe baza analizei instalrii echipamentelor de msur asincrofazorilor n rile avansate tehnologic, se apreciaz c acoperirea unui procent de 20-30 % din nodurile reelei(nu mai puin de 12 noduri, n prima etap) este o decizierezonabil.

4. Describing the suggested solution The system we suggested [5] to measure the synchro-

phasors (Fig. 3) is designed to acquire data in twelve 400 kVpower substations. This implies setting up a PMC type of measuring, monitoring and local control unit (MMLCU), a central unit for archiving and visualizing the measure-ments (AVM) that will be installed in National Power Dispatching Operating Unit (NPDOU) Bucharest and five workstations for analyzing and visualizing (AV) set up within those 5 Territorial Dispatching Units (TDU). The architecture of the measuring system of synchrophasorsis an open type one, in order to ensure the possibility of upgrading it with subsequently developed software and hardware functions.

In order to establish the locations for the measuring points, a study has been conducted based on the following criteria: setting them up in the critical buses, in order to monitor

their stability; in close vicinity of large power plants 400 kV buses,

for monitoring the oscillations and dynamic stability problems;

at the ends of the tie-line, where congestion is frequent,in order to observe the thermal load limit;

at the ends of the neighboring subsystems tie-lines, in order to ensure phasors observability in the entire U.C.T.E. system and gauge it against a single reference, unique in the U.C.T.E., for all phasors;

the installed equipment must improve the observability conditions to estimate the state of the entire system. NPDOU has selected the 12 measuring points as fol-

lows: Gutina, Bucureti-Sud, Roiori, C.N.E. Cernavoda, Isaccea, Porile de fier, Tnreni, Braov, Iernut, Arad, Mintia, Ndab.

Based on installation analysis of the synchrophasors measuring equipment in technologically advanced coun-tries, it was concluded that covering a percentage of 20-30 % of the network nodes (no less than 12 nodes, in the first stage) is a reasonable decision.

In the 12 above mentioned power stations, eachMMLCU will consist of a measuring subsystem (MSS) containing all the necessary equipment to acquire the syn-


n cele 12 staii electrice menionate, fiecare EMMCva fi compus dintr-un subsistem de msur (SSM) formatdin echipamentele necesare pentru msurarea sincrofazo-rilor, precum i dintr-un subsistem de sincronizare (SSS). EMMC este realizat din echipamentele de sincronizareadecvate (anten i surs de timp) prin care se asigurtuturor echipamentelor de msur, referina unic de timpnecesar sincronizrii tuturor fazorilor. Componentelecelor 2 subsisteme sunt echipamente numerice.

UCCAV existent la nivel central, este compus dinechipamente de comunicaie pentru concentrarea sincro-fazorilor msurai n puntele locale. Ea va colecta dateletransmise din cele 12 puncte de msur i le va pune ladispoziia celor 6 staii de lucru de tip PC (una la DEN icate una la fiecare din cele 5 DET-uri), pe care vor rulapachete software de arhivare i vizualizare. Staia de lucru cu software-ul aferent aparine subsistemului de colectare, arhivare i vizualizare (SSCAV). Cele 3 subsisteme SSM,SSS i SSCAV alctuiesc nucleul sistemului de msuraresincronizat a fazorilor (SMSF).

chrophasors, as well as of a synchronization subsystem(SSS). MMLCU contains the appropriate synchronizing equipment (antenna and time source), through which the single time reference necessary in order to synchronize all the phasors will be supplied to each measuring equip-ment. Both systems use digital equipment.

The central level AVM consists of communication equipment, in order to concentrate the synchrophasorsmeasured in the local points. It will collect all the data sentfrom the 12 measuring points and it will convey them to the 6 PC type workstations (one at NPDOU and the rest at each of the 5 TDUs), on which will be running archiving and visualizing software packages. The workstation, to-gether with the corresponding software is part of the col-lecting, archiving and visualizing subsystem (CAVS). The 3 subsystems (MSS, SSS and CAVS) form the core of the synchronized measuring system for phasors(SMSP).

Fig. 3. Arhitectura propus pentru sistemul de msurare sincron a fazorilor. Fig. 3. The suggested architecture for the synchrophasor measuring system.

n cadrul EMMC (Fig. 4), SSM este capabil s achizi-ioneze tensiunea secundar de 100 V, de pe barele de400 kV aferente punctului de msur. Este de asemeneaposibil msurarea a 2 seturi de cureni de 1 A de la trans-formatoare de curent, montate pe o linie magistral. Toatemrimile anterior menionate, sincronizate n timp suntconforme cu standardele IEEE 1344 sau IEEE C37.118.

Echipamentele de msur trebuie s asigure o eroaretotal sub 1% n condiii specifice ale tensiunii de msur, frecvenei sau curenilor.

Within the MMLCU (Fig. 4), MSS is able to acquire the secondary voltage of 100 V, from the 400 kV buses corresponding to the measuring point. There are also pos-sibilities to measure two sets of 1 A current from the currenttransformers installed on a tie-line. All measured voltage and currents synchrophasors are in accordance either with IEEE 1344 or with IEEE C37.118 standards.

The measuring equipment must ensure a total error lessthan 1% in specific voltage, frequency and current condi-tions.


SSS este componenta esenial SSM. El asigur referinaunic de timp necesar msurrii sincrone a fazorilor. Sebazeaz pe recepia informaiei de timp de la sistemul desatelii GPS. Subsistemul de sincronizare este format din antena GPS i din ceasul sincronizat prin satelit, capabils realizeze sincronizarea necesar a fazorilor. Cerinaprincipal solicitat receptorului GPS (ceasului de sincro-nizare) pentru a putea fi folosit n sistemele de msuraresincron a fazorilor este precizia de 1 s.

SSS, mpreun cu SSM, se vor monta ntr-un dulap metalic, n structura de tip rack de 2200x800x600mm,prevzut cu u transparent n fa, cu deschidere de 150de grade. Echipamentele din dulap se vor alimenta la220Vc.c. din serviciile proprii de curent continuu ale Sta-iei, prin intermediul unui bloc de alimentare, montat ndulap (Fig. 4).

SSS is the main part of MSS. It ensures the unique timereference necessary to the phasors synchronization. It is based on receiving the time information from the GPS satellite system. The synchronization subsystem consists in the GPS antenna and the satellite synchronized watch, capable of carrying out the synchronization required by the phasors. The main requirement for the GPS receiver (the synchronization watch), in order to use it in the phasorssynchronization has 1 s accuracy.

The SSS, together with the MSS, will be installed in a metal case, accommodating a 2200 x 800 x 600 mm rack structure, with a see-through door that can open at 150 degrees. The equipment in the case will be supplied with 220Vd.c. via the continuous current services of the sub-station itself, through a supply module, installed within the case (Fig. 4).

Fig. 4. Schema sistemului local de msur a sincrofazorilor Fig. 4. Local synchrophasors measuring system diagram.

Fig. 5. Schema bloc a subsistemului de colectare /arhivare /vizualizare a sincrofazorilor.

Fig. 5. CAVS diagram.


Pachetele software ale SSCAV (dispus la dispecer i acrui schem este prezentat n Fig. 5) trebuie s realizezeurmtoarele funcii: a) Colectarea informaiilor care trebuie s permit: utilizarea ambelor protocoale de comunicaii IEEE 1344i IEEE C37.118 specifice sincrofazorilor, n scopulfacilitrii extinderii ulterioare a sistemului;

achiziionarea informaiilor din cel puin 30 de punctede msur (in prima etapa 12 puncte de msur);

transmiterea sincrofazorilor ctre staia de lucru de ladispecer i din cadrul celor 5 DET-uri.

b) Arhivarea trebuie s asigure: capacitatea de arhivare minim s corespund unei rate

de 20 mesaje pe secund provenite de la toate punctelede msur pe o durat de 30 zile;

posibilitatea fixrii numrului de canale, a frecveneide arhivare i a capacitii maxime de stocare;

c) Vizualizarea simultan a informaiilor n ferestre multi-ple, a dinamicii trendului pentru mrimile digitale i amai multor fazori selectai n funcie de necesiti. De asemenea, software-ul va trebui s permit setarea

unor condiii de alarm, iar n cazul cnd limitele impusesunt depite, operatorul s fie ntiinat pentru a putea luadeciziile potrivite.

Echipamentele aferente subsistemului de colectare /arhivare / vizualizare se vor monta intr-un dulap metalic, n structur de tip rack, de 2200x800x600mm, prevzut cu u transparent n fa, cu deschidere de 150 de grade. Dulapul va fi amplasat n cadrul UnO-DEN Bucureti. Echipamentele din dulap se vor alimenta cu tensiunea de 230Vc.a., prin intermediul unei surse neintreruptibile (UPS).

The CAVS software packages (Fig. 5) must ensure the following functions: a) Collecting the information that allows: to use both IEEE 1344 and IEEE C37.118 communi-

cation protocols, for synchrophasors, in order to facili-tate the subsequent extension of the system;

to acquire the information from at least 30 measuring points (in the first stage, 12 measuring points);

to send the synchrophasors to the workstation from the dispatcher and from the 5 TDU.

b) Archiving that ensures: the minimum storing capacity of 20 messages per sec-

ond from all the measuring points for a period of 30 days;

it is possible to set up the number of channels, the ar-chiving frequency and the maximum capacity of stor-age.

c) Visualizing the information in multiple windows visi-ble at the same time, the evolution trend for the digital quantities and several phasors chosen as the necessity arises. Moreover, the software must allow setting alarm con-

ditions and, in case the limits imposed are exceeded, the operator must be warned in order to take the appropriate decisions.

The equipment that forms the CAVS will be installed in a metal case, accommodating a 2200 x 800 x 600 mm rack structure, with a see-through door that can open at 150 degrees. The case will be placed within the UnO-DENBucharest. The equipment in the case will be supplied with 220Va.c. by an uninterruptible power supply (UPS).

5. Concluzii

Sistemul de msur a sincrofazorilor reprezint un important salt tehnologic n monitorizarea i controlulSEN i cu certitudine va devenii o unealt esenial delucru a dispecerilor.

Principalele beneficii estimate a fi aduse de msurareasincrofazorilor, fr a avea pretenia de a le cuprinde iepuiza pe toate, sunt: a) Sistemul de msur a sincrofazorilor asigur semnalizarea

timpurie a apariiei condiiilor de instabilitate a SEN, ceea ce va permite: detectarea instabilitii poteniale cauzate de valori

anormale ale tensiunilor, a frecvenei i a depiriilimitei de ncrcare termic a liniilor din reea,

luarea n timp real a deciziilor adecvate care s contra-balanseze situaiile limit periculoase,

oprirea prin contramsuri judicios stabilite a efectuluide insularizare n cascad.

b) Monitorizarea dinamicii SEN furnizeaz informaii per-tinente n timp real care judicios utilizate fac posibil: funcionarea sigur a sistemului n condiii de apariie

a unor congestii sau perturbaii, exploatarea n condiii de securitate a liniilor electrice

magistrale, adaptabilitate la funcionarea n apropierea limitei

termice a echipamentelor, restaurarea sistemului supravegheat n timp real, in

urma unui colaps parial sau total.

5. Conclusions The measuring systems of synchrophasors are an im-

portant technological leap in monitoring and controlling the Power System and it will undoubtedly become a vital tool in the dispatcher work.

Not presuming to state every single one, the main benefits brought by measuring synchrophasors are: a) The measuring system of synchrophasors ensures the

timely signalizing of instability conditions for National Power System, and this will allow, in turn: to detect the potential instability generated by abnor-

mal voltage & frequency values and to detect the ex-ceeding of the heat liberation limit for the tie-lines,

to take the appropriate decisions for dealing with dan-gerous limit scenarios in real time,

to stop, through sensible countermeasures, the cascad-ing insulation effect.

b) Real time monitoring of the National Power System dynamics ensures relevant information which, used wisely, allows: the safe system operation in congestion or perturba-

tion cases, tie-line security operation, the adaptable operation close to the thermal limit of

the equipment, the real time monitored system restoring, subsequent

to a partial or global failure.


c) Monitorizarea n timp real a nodurilor critice din SEN: asigur realizarea livrrii energiei electrice n condiii

calitative optime, crete securitatea alimentrii consumatorilor importani, evit separarea neateptat fa de sistem a unor noduri

sau grupuri de noduri. d) Realizarea unei precizii foarte mari (1 s) de sincro-

nizare a msurrii fazorilor permite obinerea unei erorimici (sub 0.1 grade) pentru determinarea unghiuriloracestora, ceea ce face posibil urmrirea n timp real aregimurilor tranzitorii cu constante mici de timp.

e) Capacitatea de a efectua analize post avarie foarte finei extinse pentru stabilirea cauzelor unor avarii i luareacelor mai potrivite msuri.

f) Monitorizarea sistemului se realizeaz sugestiv i comodcu ajutorul unor imagini care permit:, raportarea datelor la un sistem unic de referin a un-

ghiurilor, afiarea tendinei de evoluie a unor mrimi eseniale:

frecven, unghiuri de sarcin, temperaturi de funcio-nare,

afiarea la scar a fluxurilor circulaiei de puteri, vizualizarea repartizrii spaiale a ncrcrii sistemului cu

evidenierea zonelor cu deficit sau cu surplus de sarcin, afiarea unor diagrame cu oscilaiile unor mrimi di-

namice: unghiuri, tensiuni, cureni, prezentarea grafic unor mrimi de calcul i a unor ca-

racteristici eseniale, standardizarea procedurilor de monitorizare si compati-

bilizarea acestora la nivelul continental Power System, vizualizarea unor portrete (semnturi) specifice unor

fenomene, cu care s se stabileasc n mod obiectivexistena si modul de evoluie a unor categorii de re-gimuri de funcionare.

g) Posibilitatea coordonrii eficiente proteciilor i auto-maticii de sistem.

c) The real time monitoring of the critical buses in Na-tional Power System: ensures the optimal qualitative conditions for power

delivering, raises the safety in supplying important consumers, avoids the sudden breaking away of various system

buses or groups of buses. d) A very high precision (1 s) in synchronizing the phasor

measuring allows a small error (less than 0.1 degrees) in determining their angles, which makes possible to trackin real time the transitory small time constant regimes.

e) The option to carry out very thorough and extended post-failure analysis in order to establish the causes and the most appropriate measures.

f) The monitoring of the system is carried out suggestivelyand conveniently due to images that allow: to gauge the data against a single angle reference system, to display the evolution tendency for the relevant quanti-

ties: frequency, load angles, operating temperatures, to show, on scale, the power flows, to view the spatial distribution of the system load,

pointing out the underloaded or overloaded areas, to present various charts illustrating the oscillations of

certain dynamic quantities: angles, voltages, currents, to ascertain, graphically, various quantities and essen-

tial characteristics, to standardize the monitoring procedures and to make

them compatible on the continental Power System level, to view various portraits (signatures) specific to certain

phenomena based on which it is possible to establish, objectively, various categories of operating regimes.

g) The possibility to control, efficiently, the system pro-tections & automatics.

Bibliografie (Bibliography) [1] M. Adamiak, W. Premerlani, B. Kasztenny, Synchrophasors: Definition, Measurement and Application, Power Systems 2005

Conference Distributed Generation, Advanced Metering and Communication, March 8-11, 2005, Madren Center, Clemson Uni-versity, Clemson, SC, USA.

[2] M.A. Donolo, Advantages of Synchrophasor, Measurements Over SCADA Measurements for Power System State Estimation, Application Note AN2006-10.

[3] C. Anderson, B. Fearn, A. Guzman, R. Moxley, Using SEL-421 Relay Synchrophasors in Basic Applications, SEL Application Guide, Volume I AG2002-08.

[4] G. Benmouyal, A. Guzmn, Synchronized Phasor Measurement in Protective Relays for Protection, Control and Analysis of Electric Power Systems, 29th Annual Western protective relay conference Spokane, Washington October 22-24, 2002.

[5] N. Chiosa, N. Pantazi, B. Lustrea, I. Borlea, C. Brbulescu, Sistem de Msur Sincron a Fazorilor. Studiu de soluie. Martie 2007. Lucrarea 313. CNTEE Transelectrica.

2.1. Repere ale evoluiei sincrofazorilor2.1. Landmarks in the evolution of synchrophasors2.3. Definiii2.3. Definitions2.4. Diverse probleme legate de utilizarea sincrofazorilor2.4. Various synchrophasors application aspectsSynchrophasorsc) Vizualizarea simultan a informaiilor n ferestre multiple, a dinamicii trendului pentru mrimile digitale i a mai multor fazori selectai n funcie de necesiti.c) Visualizing the information in multiple windows visible at the same time, the evolution trend for the digital quantities and several phasors chosen as the necessity arises.

Documents

Sincrofazori Sen