Transmission network angle stability protection based on synchrophasor data in control centre

Angle stability appears in many forms in transmission network. There are small active power oscillations which do not endanger the normal operations whereas medium and large oscillations have implications on normal operations. These latter kinds of oscillations in some cases develop in out of step condition, which is dangerous disturbance with serious impact on transmission network and generating units. Transmission network operator’s challenges and obligations are to treat in the right manner angle stability issues in their network. Controlling and protecting network needs to be done in efficient way in order to disconnect disturbance quickly and prevent abnormal network operation without exporting disturbance in surrounding networks. Synchrophasor measurements in control centre offer a platform, which responds in a new way on angle stability in transmission network. Those measurements which are collected in phasor data concentrators, which is a part of Wide Area Monitoring will be used for creating out of step protection. This is the first step to extended system to Wide Area Monitoring Protecting And Control (WAMPAC). Paper gives progress of such project in Croatian Transmission Network Operator (HOPS). Firstly, there will be stated motives for development of new out of step protection based on synchrophasor measurements. Some feasibility aspect elaborated with emphasis on communications latency. Furthermore, designed Matlab model for transmission network and protection with small portions of simulations results and analyses presented in paper reveal potential of proposed solutions. This new protection is based on using voltage angles values from phasor data stream in phasor data concentrator

Synchronized phasor measurements in a dual layer hybrid state estimator

Arhitektura predloženog dvoslojnog hibridnog procjenitelja stanja polazi od linearnog procjenitelja stanja koji kao ulazne veličine koristi sinkronizirana mjerenja fazora te računa stanja sabirnica s ugrađenim jedinicama za sinkronizirano mjerenje fazora i stanja njima susjednih sabirnica. Izračunata se stanja koriste za dobivanje pseudo-mjerenja koja se zatim u drugom sloju obrađuju zajedno s konvencionalnim mjerenjima iz SCADA sustava. S obzirom da je veza konvencionalnih mjerenja i varijabli stanja nelinearna, u drugom se sloju koristi iterativna metoda najmanjih kvadrata s težinskim faktorima kako bi se odredilo stanje cjelokupnog sustava. Razvijena je formulacija ispitana na IEEE sustavima i na modelu hrvatskog prijenosnog elektroenergetskog sustava. Dobiveni su rezultati uspoređeni s procjeniteljem stanja zasnovanom na klasičnoj teoriji koji koristi konvencionalna mjerenja, kao i s još jednim hibridnim modelom. Hibridni procjenitelj stanja zasnovan na predloženoj arhitekturi omogućuje točniju procjenu stanja s poboljšanim filtriranjem pogrešaka u skupu mjerenja te s poboljšanom konvergencijom proračuna.The architecture of the proposed Dual Layer Hybrid State Estimator starts with the linear state estimator that only takes synchrophasors as inputs and calculates states of the buses with the deployed Phasor Measurement Units (PMUs) and their adjacent buses. These states are used to obtain the pseudo-measurements that are processed together with conventional SCADA measurements. As the relationship between the conventional measurements and the state variables is nonlinear, in this layer the iterative weighted least squares method is applied to estimate state of the complete power system. The developed formulation was tested on the IEEE systems as well as on the Croatian transmission power system model. The obtained results are compared with the classical solution that uses the conventional measurements and with another hybrid model. The hybrid state estimator based on the proposed architecture offers more accurate state estimation with enhanced filtering of measurements errors and with improved convergence capabilities

Transmission network angle stability protection based on synchrophasor data in control centre

Angle stability appears in many forms in transmission network. There are small active power oscillations which do not endanger the normal operations whereas medium and large oscillations have implications on normal operations. These latter kinds of oscillations in some cases develop in out of step condition, which is dangerous disturbance with serious impact on transmission network and generating units. Transmission network operator’s challenges and obligations are to treat in the right manner angle stability issues in their network. Controlling and protecting network needs to be done in efficient way in order to disconnect disturbance quickly and prevent abnormal network operation without exporting disturbance in surrounding networks. Synchrophasor measurements in control centre offer a platform, which responds in a new way on angle stability in transmission network. Those measurements which are collected in phasor data concentrators, which is a part of Wide Area Monitoring will be used for creating out of step protection. This is the first step to extended system to Wide Area Monitoring Protecting And Control (WAMPAC). Paper gives progress of such project in Croatian Transmission Network Operator (HOPS). Firstly, there will be stated motives for development of new out of step protection based on synchrophasor measurements. Some feasibility aspect elaborated with emphasis on communications latency. Furthermore, designed Matlab model for transmission network and protection with small portions of simulations results and analyses presented in paper reveal potential of proposed solutions. This new protection is based on using voltage angles values from phasor data stream in phasor data concentrator

Real time power swing monitoring in hydro power plant supported by synchronized measurements

Dinamički poremećaji u elektroenergetskom sustavu odražavaju se na rad generatora i uzrokuju niz poremećaja od kojih je značajno njihanje snage, koje može dovesti do prorada zaštita, ispada generatora iz pogona i odvajanja od mreže. Dosadašnja primjena sinkroniziranih mjerenja u području njihanja snage uglavnom se odnosila na prijenosni sustav te gubitak sinkronizma na dalekovodu. U ovom radu prikazano je izvorno rješenje za nadzor njihanja snage u hidroelektrani u stvarnom vremenu zasnovano na sinkroniziranim mjerenjima i Prony analizi, koja je osnova za ublažavanje poremećaja. Prony analiza je korištena za analizu frekvencije, prigušenja ili raspirivanja i amplitudu njihanja snage na osnovu sinkroniziranih mjerenih vrijednosti fazora napona. Uvođenjem sinkroniziranih mjerenja u nadzor njihanja snage omogućava se detekcija i nadzor njihanja snage u stvarnom vremenu, što klasičnim metodama nije bilo moguće. Zaključno, u radu su prikazani rezultati implementiranog nadzora njihanja snage u stvarnom vremenu na primjeru stvarne hidroelektrane.Dynamic disturbances in the electric power system exert influence on the operation of generators and cause several other disturbances, such as a power swing, resulting in the activation of protections, the stalling of generators and their disconnection from the grid. The application of synchronized measurements in the field of power swing has mainly been focused on a transmission power system and on the loss of synchronism on power lines. In this paper the original solution for real time power swing monitoring in a hydro power plant based on synchronized phasor measurements and Prony analysis is proposed, which is a basis for mitigation of disturbances. Prony analysis is used for the analysis of frequency, decreasing or increasing amplitude of oscillations based on the synchronized measurements of voltage phasors. Using the synchronized phasors measurements for power swing monitoring allows detection and monitoring of power swings in real time, which was not possible with classical methods. To conclude with, the results of the implemented real time monitoring system in the real hydro power plant are given in the paper

A noninvasive inclusion of synchrophasors in the power system state estimation

Rad istražuje primjenu sinkroniziranih mjerenja fazora, dostupnih iz jedinica za sinkronizirano mjerenja fazora (PMU), u estimaciji stanja elektroenergetskog sustava. Kako bi se izbjegla promjena vrste mjerenja koja ulaze u klasičan estimator stanja korišten u centru vođenja, predloženi model koristi fazore napona i struje za izračun pseudo mjerenja poput pseudo-napona, tokova snage i injekcija snage. Izračunata se pseudo-mjerenja zatim zajedno s amplitudama fazora napona te konvencionalnim mjerenjima primjenjuju u iterativnoj proceduri. Kao test sustavi korišteni su IEEE test sustavi s 14, 30, 57 i 118 čvorišta, kao i matematički model hrvatskog prijenosnog elektroenergetskog sustava. Rezultati dobiveni simulacijom su uspoređeni s rezultatima klasičnog estimatora stanja, koji koristi samo konvencionalna mjerenja. U radu je istražen utjecaj kuta fazora napona na performanse estimatora stanja.The paper investigates the application of synchronized phasor measurements, which are available from Phasor Measurement Units (PMUs), in the power system state estimation. In order to avoid changes in the type of the input measurements of the classical state estimator, which runs in the control centre, the proposed model utilizes voltage and current phasors to calculate pseudo-measurements such as pseudo-voltages, power flows and power injections. These pseudo-measurements are used together with the voltage phasor magnitudes and the conventional measurements in the iterative procedure. The IEEE 14, 30, 57 and 118 buses test systems as well as the mathematical model of the Croatian transmission power system were used as the test systems. The results of the simulation were compared with the classical state estimator, which uses only conventional measurements. The effect of the voltage phasor angles on the state estimator performance was investigated