Emeka
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I run my loadflow using fixed slope newton raphson but it converges after 15 iterations, does it mean that my results on the model is unstable?

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Thank you for your reply. I ran the loadflow and it converge in 15 iterations after which I proceeded to run the dynamic simulation with all dynamic models included. I followed the normal process of dynamic simulation but I keep getting the results on 'network not converged at time'.

Emeka ( 2015-09-17 06:01:57 -0600 )edit

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answered 2015-09-16 08:47:37 -0600

jconto
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updated 2015-09-19 19:17:47 -0600

Load flow convergence in a given number of iterations does not correlate with model instability. It is simple an indication of how far the initial network states (V and angles) are from producing a mismatch (in P and Q) within the tolerance specified in the tool. Model instability is tested with dynamic tools, mainly, a dynamic simulation.

When a dynamic simulation gives 'network not converged' errors, you can try the following:

review the (newest) models parameters for anomalies. Data entry errors.
lower delta t, integration stepsize.
check that bus voltages (V, angle) and Gens P & Q are within limits in the base case. Check the 'SUSPECT CONDITIONS' entries after the STRT activity.
Start from a known dynamic set that 'flatstart', it gives var's flat lines to a no-disturbance test, and then sequentially add the new models and repeat the flatstart until the problem is identified or no problem is found. Once all new models are added and you still get a flatstart, then you are ready for a full dynamic simulation. Post your findings.
....

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answered 2015-09-27 18:19:37 -0600

Emeka
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Hi JConto,

I have initialized my OVERLOADED MACHINE SUMMARY: BUS# X-- NAME --X BASKV ID 505 OLORUNSOGOG10.500 1 2501 KAINJI8 16.000 1 2701 KAINJI10 16.000 1 3001 KAINJI9 16.000 1 16013 OLORUNSOGOG15.000 1 16029 OLORUNSOGON10.500 1 16030 PAPALANTO GE10.500 1 16034 OLORUNSOGOG15.000 5 16035 OLORUNSOGOG13.800 1 16036 OLORUNSOGOG13.800 5 16037 OMOTOSHOGTB15.000 5 16038 OLORUNSOGOG15.000 1 16039 OLORUNSOGOG15.000 5 26000 OMOTOSO G-BU15.000 2 26006 OMOTOSO GEN 15.000 1 26007 OMOTOSHOGTB15.000 5 36012 SHIROHYD1 16.000 1 86012 AFAM VI - 4 11.500 1 86032 ALAOJIGTB1 15.000 5 dynamic data and initial conditions are ok but I got some reports for my overloaded machines see below. How do I go about reducing solving this overloaded machine problems? MW MVAR QMAX QMIN ETERM CURRENT PF MVABASE X T R A N GENTAP ZONE AREA SWING 41.9 23.0 23.0 -15.0 0.9474 50.4 0.8766 52.3 1 1 57.5 -29.8 25.0 -30.0 1.0000 64.8 0.8876 85.0 1 3 57.5 -29.8 25.0 -30.0 1.0000 64.8 0.8876 85.0 1 3 57.5 -29.8 25.0 -30.0 1.0000 64.8 0.8876 85.0 1 3 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 17 1 126.0 60.0 60.0 -40.0 0.9786 142.6 0.9029 157.0 13 1 126.0 60.0 60.0 -40.0 0.9786 142.6 0.9029 380.0 13 1 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 13 1 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 13 1 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 13 1 41.9 23.0 23.0 -15.0 0.9681 49.4 0.8766 52.3 13 2 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 13 1 41.9 23.0 23.0 -15.0 0.9339 51.2 0.8766 52.3 13 1 41.9 23.0 23.0 -15.0 0.9939 48.1 0.8766 52.3 22 2 41.9 23.0 23.0 -15.0 0.9939 48.1 0.8766 52.3 20 2 41.9 23.0 23.0 -15.0 0.9681 49.4 0.8766 52.3 23 2 150.0 79.0 79.0 -30.0 0.9787 173.2 0.8848 174.0 30 3 200.0 124.0 124.0 -83.0 1.0315 228.1 0.8499 210.0 80 8 112.5 -48.8 84.4 -56.3 0.9247 132 ... (more)

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I have tried running the dynamic simulation but after introducing a fault, the psse freezes and tries to reboot itself or it says network not converge at time =0.02. I have my initial conditions ok, I have removed all gen P and Q limits but I still do not have dynamic solution. I am really confused

Emeka ( 2015-09-27 19:38:24 -0600 )edit

All machines in you overload table are at their Qlimit. A fault imposed higher reactive infusion, but having no margin, the system enters into a voltage collapse condition. Try reducing the load in the system and perform a PV analysis to identify the voltage margins. test: Add an Statcom.

jconto ( 2015-09-28 09:15:12 -0600 )edit

Hi Jconto, I have tried everything you said but still no head way. Please send me your email address so you can look at it and see how you can assist. thank you

Emeka ( 2015-11-04 01:57:27 -0600 )edit

dynamic flatstart is a time-consuming effort. I will take a look at your data set but unless it is an obviuos fix, do not expect a quick answer. My email is jcpotencia@mail.com

jconto ( 2015-11-04 12:39:41 -0600 )edit

Hi Jconto, Please do know the procedure to model the PV system on PSSE for the dynamic solution?

Emeka ( 2016-01-20 01:55:36 -0600 )edit

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Number of Iterations for loadflow on PSS/E

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