I think you should verify the bus and line data.

In bus data, make sure that one bus is slack bus having no reactive power limits. There may be error in entering the voltage. When you don't know the voltage at a bus, take it 1.0 pu.

In line data, the reactances must be realistic, there may be some or one line having very large reactance due to typing error.

First of all, if you disable the reactive power limits in the load flow option, then your power flow will converge regardless of the reactive power limits and you can see which generator(s) that violate these limits. This way you can see if the reactive power limits for each generator are sufficient or not. 

Different machines might have different operational limits, so you should rely on the vendor datasheet in order to construct a realistic operational range of the machine.

http://www.neos-guide.org/sites/default/files/capability_curves.pdf

The above link may help you.

you can make the PV bus (which voilates the limits) as PQ bus and then your network load flow will converge 

The reactive power supplied by a generator in the load flow sollution depends on the control mode choosen. Are you using voltage control mode (PV bus) or power factor control mode (PQ Bus)? If your are using voltage control mode and the power flow fails to converge then try the option suggested by Roni Imawan. If the sollution still does not converge then there is problably an error in your network model. If the sollution converges it means that the voltage control set point can not be achieved with the reactive power limits asigned to the generator.

Dear Shaibu Ibu Mludi

Please check the loads PF in the system. Usually they are 0.95 and also transmissiion lines data. Maybe some are with incorrect high X value so you have unreal demand for reactive power. You also need to have on generator or utility bus as a Slack bus. Follow  abow instruction for PV generator node and set it with unlimited Q.

Depending on how complex is your network, try replacing the generator with a slack bus, and hit a load flow calculation. If the model doesn't converge then you have a network model problem. If the reactive power is still high, you have a problem modeling either the consumer or the network itself. Try to identify the problem.

I agree with Mr. Kriukov. If the model has a declared slack bus, there should be no problem in load flow convergence unless there is a problem with network modelling. If the reactive power limit of generator is violated, this would appear simply as a notice in the result window. But still the load flow would converge.

I think you should verify the bus and line data.

In bus data, make sure that one bus is slack bus having no reactive power limits. There may be error in entering the voltage. When you don't know the voltage at a bus, take it 1.0 pu.

In line data, the reactances must be realistic, there may be some or one line having very large reactance due to typing error.

If you still not solve the problem, You can send me a file privately and I will check it. Please use version 15.0 of Powerfactory

Srete

MVAR limiation can be find out by calculating var requirement to meet grid code..that would be your MVAR Limitation range from -ve( leading ) to +ve (lagging) reactive power.

if you are using Generator bus as slack bus..then MVAR flow towards grid/power system network would be depended on requirement of network. And it will not obey/follow the VAR limitation.

But if you are using as voltage control bus then it will be in the range. And only maintain the voltage at respective bus/ connected bus that would be your point of common coupling (PCC). 

if you still find any problem then do send me pfd file (Powerfactory 15.1 version).

thanks

Best Regards,

M. Amer Saeed

The voltage is due to the electrical generator, the  current is due to  the electrical consumer, the reactive power is the result of the interaction between generator and electrical consumer. The problem is more complex; the analysed model is simple;  the variation in time, about current, voltage, active and reactive electrical power must be analysed, in the considered situation. It may exist others component of electrical power(non-symmetric power, non-fundamental power), read:

snet.elth.pub.ro/snet2012/volume/P1.23.pdf

www.energy-cie.ro/archives/2011/3.14-matica_l2_cie[1].pdf

In DIgSILENT Powerfactory software you have option for generator modeling in which you can set min and max reactive power limits of capacitive and inductive production of generator. Generator can work  to maintan the voltage on its local bus or work in P, cos phi mode to maintain power factor and deliver active power P.

You can also add capability cure of generator if you have it from producer.

So the amount of reactive power, most be inductive and depends of loads and lines and transformer parameters. So check line lenghts and uk % of transformers and ractive power of loads.. You also need to have another bus with Utility called slack bus and set it as SL node.

Ensure your network layout, configuration (mesh or not) and parameters are modelled correctly and satisfactory - check line lengths, per unit values, SM parameters and capability curves. Is your system dynamic with time-varying loads? Construct a realistic operation for each machine and extend the operation limits, to see if it converges.