Understanding the behavior of Exciter, PSS & Governor during Transient Stability studies???Syed Mujtaba HassanReal Time operation Engineer at K-ElectricTop ContributorDear All,Hopefully all of you would be fine..I am modelling a interconnected Power system to perform the Transient stability analysis...However, more than Data entry , i want to understand the contribution/ behavior of Governor, exciter and PSS and/or other components of Power system during Transient condition.....

RegardsSyed Mujtaba Hassan Like (4) Comment (6) Share Follow Reply Privately 4 days agoCommentsKhemmarat Hemmachatluechai,Syed Arshadand2 otherslike this6 comments AlanAlan MaltzChief Electrical Engineer, RAM ConsultingSyed, All of the following descriptions are highly dependent upon the type/tuning/settings of the devices and the system they are connected to.

The governor controls the prime mover's power output in an attempt to hold the frequency and/or real power generation constant. The excitation system controls the generator's excitation level in an attempt to hold the voltage and/or the reactive power constant.

Since these two control systems operate in quadrature with each other they exert only incremental actions on each other and are not interconnected. On the other hand the grid that the prime mover/generator is connected to does in fact react to the actions of both, hence the PSS (Power System Stabilizer) was developed.

It is a tightly integrated control system that provides the missing connection between the two by carefully adjusting the real time response of both systems in a coordinated fashion, based upon what is happening out on the grid. The design/application/tuning of a PSS is as much an art as it is a science and requires an in depth knowledge of the dynamics of the particular prime mover/generator combinations as well as the reaction of the grid to various transient events.

The topic is too broad to be covered to be covered here, but there are many fine technical papers from IEEE, CIGRE, and others that can easily be found by using your favorite search engine on the term "Power System Stabilizer"

Alan Like (7) Reply privately Flag as inappropriate 4 days agoRaymond N.,Nagarajan K.and5 otherslike this Mohamed EissaMohamed Eissa AlhajElectrical Engineer at Sudanese Electricity Distribution Co.LtdGreat Like Reply privately Flag as inappropriate 3 days ago someshsomesh bhattacharyaStudent at Indian Institute of Technology, DelhiThe actions of governor, exciter and PSS in a multimachine power system during a transient operation such as a fault can be seen very easily in any dedicated power system software such as DIGSilent, PSSE or anything you are comfortable with. You can try introducing a fault of a few cycles and remove it and see the oscillatory behavior with or without any of these components. A properly tuned exciter helps in better transient shaping. But if you want to completely diagnose the behavior of such control systems, only transient studies may not help. You will have to perform a small signal analysis with the PSS and the exciter modeled along with the swing equation and the flux decay equation of the alternator. The participation factors will tell you the contribution of the components. These are available very maturely in any power system dynamics book and 1000's of papers have been published. Like (1) Reply privately Flag as inappropriate 3 days agoSfiso M.likes this SfisoSfiso MtsweniSnr Technician HV Lab Wits UniversityAlan is on point Like Reply privately Flag as inappropriate 2 days ago ShahramShahram Montaser KouhsariProfessor of University. Power system at Amirkabir University of TechnologyUse a real time simulator to get more familiar with the actions of Governor and AVR by playing with the following exampled networks (Pleas also see the note below before clicking on the links:)

* AVR

Basic network:http://www.intelectri.com/NETWORK/l/IN.pdfPlay on line:http://www.intelectri.com/linkedin/POUYAl.BAT

* Governor:

Basic network:http://www.intelectri.com/NETWORK/h/IN.pdfPlay on line:http://www.intelectri.com/linkedin/POUYAh.BAT

* PSS (small example network not included, Ask me to include it.

(Note: Clicking on the play on line links below will download an open source batch file (1KB). Windows operating system will usually warn you about the danger of any batch file running on computer.The file has been set as an open source deliberately, and so you can view the file contents, be sure that there is no harm in there. Click on the downloaded file to go to the simulation. If you have not already installed POUYA software on your computer, or it is not the latest version of POUYA it will guide you for installing POUYA.) Like (2) Reply privately Flag as inappropriate 2 days agoAli Reza N.,Soley Atashbarlike this AndrewAndrew BennettPrincipal Software Engineer at The MathWorksFor a synchronous generator, there are a few quantities that need to be controlled:* the rotational frequency of the machine* the magnitude of the output voltage* the relative phase of the generator output voltage to the rest of the network

The frequency is directly related to the amount of power into the generator from the prime mover. A governor monitors generator shaft speed and alters the throttle of a gas turbine/diesel, or steam valve for coil/oil/nuclear to ensure it is as desired - usually nominal frequency plus or minus < 1% for a land based system, a couple of percent for a finite inertia system.

The voltage magnitude is directly related to the excitation supplied to the rotor of the generator. An Automatic Voltage Regulator monitors output terminal voltage and alters the excitation to ensure it is as desired.

The voltage control loop (AVR) operates more quickly than the speed control loop (governor).

Sometimes there can be transient oscillations on a network, real-power output fluctuates significantly. In the worst case this results in a "pole slip" whereby the rotor misses a revolution in order to correct itself - it should be avoided at all costs. A Power System Stabilizer (PSS) monitors the power output of the machine, and sometimes relative phase. It introduces a cross-term between the two control loops to damp down power oscillations by using the AVR [faster control loop] to damp down oscillations that would previously have been left for the governor [slower control loop] to deal with. Like (2) Reply privately Flag as inappropriate 2 days agoAjay J.,Soley Atashbarlike this