Ali, Firstly, you have an error in the case file. The generator set point voltage (gen(1,VG) is set to 2 pu which is incorrect. It should be around 1.0 pu.
Even after setting the generator set point voltage to 1 pu, the case does not converge because the loading surpasses the steady state loading limit causing a collapse of the bus voltages. You can see this by running the continuation power flow in MATPOWER. mpctarget = case30_1dep; mpcbase = mpctarget; mpcbase.bus(:,[3;4]) = 0.0; %% Set Pd and Qd at all buses to 0.0 [RESULTS, SUCCESS] = runcpf(mpcbase,mpctarget,mpoption('cpf.plot.level',1,'cpf.plot.bus',19)); % Run a continuation power from base case (Pd/Qd = 0.0) to target (Pd/Qd = given values in case30_1dep). The figure below plots lambda (the load scaling factor in this example) versus bus 19 voltage magnitude. Lambda= 0.0 denotes to the base case having no real and reactive power demand at the buses, while lambda = 1.0 denotes the target demand. As you can see the curve turns around at lambda=0.6 indicating the steady state loading limit has been reached. In other words, this system can only serve 60% of the given target load. Anything above 60% would cause a voltage collapse. [cid:61039831-DD0F-45E4-A312-41FDD0ABA4A9] You can do similar analysis with your second case and see that lambda goes beyond 1.0 indicating that the extra generation on the downstream bus improves the voltage stability of the system. Shri -----Original Message----- From: ALI ZAZOU Abdelkrim <abdelkrim.ali-za...@ensma.fr<mailto:abdelkrim.ali-za...@ensma.fr>> Reply-To: MATPOWER discussion forum <matpowe...@list.cornell.edu<mailto:matpowe...@list.cornell.edu>> Date: Wed, 17 Sep 2014 17:36:00 +0200 To: <MATPOWER-L@cornell.edu<mailto:MATPOWER-L@cornell.edu>> Subject: Convergence and generator Hi, I'm trying to run a simple PF with the newton method, i attached my case files with this message. And i also attached 2 pictures of the network cases. I'm working with the case30.m that i modify, i just wanted to use the line specifications. The network now have just 16 bus, 17 branch and 1 Generator(also slack bus), and the network is radial. 1st problem: The powerflow for this network ("case30_1dep.m") doesn't converge and i can't understand why, how can it be explain? But it run normally if i add a generator ("case30_1dep_ok.m") that i take from the original "case30.m". So i thought that maybe the slack bus genreation limit is reached but even with modyfing the slack bus specification in the "case30_1dep.m", it's still doesn't convergent. 2nd question: What kind of physical specification (V, P and Q limits for example) can affect the convergence. Thank you in advance for the time you will take to read my questions Best regards Abdelkrim Ali Zazou . The problem is that this loadflow don't converge and i can't understand whey, can you give me some explaination about this issue. The problem