You cannot specify both reactive power and voltage. You must specify one and 
solve for the other. The ENFORCE_Q_LIMS option that Shri mentions simply 
indicates to the program that you want to change your mind about which one you 
are specifying in the case where a reactive power limit will be violated by 
specifying V.

-- 
Ray Zimmerman
Senior Research Associate
B30 Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645



On Feb 18, 2014, at 11:06 AM, Abhyankar, Shrirang G. <[email protected]> 
wrote:

> By default, power flow does not enforce gen. reactive power limits. But you 
> can use the option ENFORCE_Q_LIMS from the mpoption options database to set 
> limits on the reactive power generation. Do help mpoption for more info.
> 
> Shri
> 
> From: Mahmoud Abdallah <[email protected]>
> Reply-To: MATPOWER discussion forum <[email protected]>
> Date: Tue, 18 Feb 2014 05:00:50 -0800
> To: MATPOWER discussion forum <[email protected]>
> Subject: Re: ask in matpower
> 
> dear sir
> I don't want specify reactive power
> I only want the change in reactive power should be negative value
> 
> thus I try to put the limit of  reactive power generated from bus 37  to be 
> only negative for example
> from -4.4 to -4
> 
> but power flow not consider this limits
> 
> what I can do to make the reactive power generated from bus 37 to be negative 
> values
> (not fixed but change in a range of negative values )
> 
> thank you in advance
> Eng. Mahmoud abdallah
> Teaching Assistant
> Ain Shams University
> Faculty of Engineering
> 
> 
> On Friday, February 14, 2014 10:33 PM, Ray Zimmerman <[email protected]> wrote:
> The point of my previous post was that the power flow was doing what you told 
> it to (assuming I was correct about you specifying it as a PV bus). If you 
> want the power flow to solve for the voltage at the bus, given a specified 
> reactive power injection (which is what you seem to be expecting), then you 
> have to specify that by changing the BUS_TYPE to PQ in the input data.
> 
> -- 
> Ray Zimmerman
> Senior Research Associate
> B30 Warren Hall, Cornell University, Ithaca, NY 14853
> phone: (607) 255-9645
> 
> 
> 
> On Feb 14, 2014, at 2:35 AM, Mahmoud Abdallah 
> <[email protected]> wrote:
> 
>> dear sir
>> 
>> this bus has wind thus it can't produce reactive power
>> 
>> all reactive power comes from the network to  bus 37
>> 
>> thus the reactive power in the power flow output should be negative  at bus 
>> 37
>> Eng. Mahmoud abdallah
>> Teaching Assistant
>> Ain Shams University
>> Faculty of Engineering
>> 
>> 
>> On Friday, February 14, 2014 12:53 AM, Ray Zimmerman <[email protected]> 
>> wrote:
>> Presumably it is specified as a PV bus, which means that you are asking the 
>> power flow program to solve for the reactive power required to maintain the 
>> specified voltage magnitude.
>> 
>>     Ray
>> 
>> -- 
>> Ray Zimmerman
>> Senior Research Associate
>> B30 Warren Hall, Cornell University, Ithaca, NY 14853
>> phone: (607) 255-9645
>> 
>> 
>> 
>> On Feb 13, 2014, at 5:36 PM, Mahmoud Abdallah 
>> <[email protected]> wrote:
>> 
>>>  dear sir
>>> 
>>> I use case 39  which has wind at bus 37
>>> 
>>> the wind at bus 37 has positive active power and negative reactive power
>>> 
>>> but when I use "runpf"   with change in active power to be 1.5 * its old 
>>> value
>>> 
>>> I find that reactive power (of bus 37) in the result of power flow becomes 
>>> positive ??? how
>>> 
>>> Eng. Mahmoud abdallah
>>> Teaching Assistant
>>> Ain Shams University
>>> Faculty of Engineering
>> 
>> 
>> 
> 
> 
> 

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