Beg your pardon the missing snippet from the previous mail is as follows:

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%% initial state
%V0 = ones(size(bus, 1), 1); %% flat start
V0 = bus(:, VM) .* exp(sqrt(-1) * pi/180 * bus(:, VA))
vcb = ones(size(V0)); %% create mask of voltage-controlled
buses
vcb(pq) = 0; %% exclude PQ buses
k = find(vcb(gbus)); %% in-service gens at v-c buses
V0(gbus(k)) = gen(on(k), VG) ./ abs(V0(gbus(k))).* V0(gbus(k));
*SAYANDEV GHOSH*
Assistant Professor
Electrical Engineering Department
Chaibasa Engineering College, Chaibasa, Jharkhand
Mob. No. - 7292880077 / 9748509620
On Tue, Aug 8, 2017 at 1:31 PM, Sayandev Ghosh <sayande...@gmail.com> wrote:
> Hello,
> I am Sayandev Ghosh, presently teaching power system in an undergraduate
> engineering college. I have done my M.Tech on Energy Science from Jadavpur
> University. I have been using MATPOWER for load flow analysis of till 118
> bus by Newton Raphson method. While doing that I am not able to understand
> the following area:-
>
>
> In the runpf() function while using Newton Raphson method the initial
> values of voltage magnitude and voltage angle have been assigned by the
> following lines (line 177 - 183):
>
> [image: Inline image 2]
> I am having a bit problem in understanding this section. Why are we
> considering the final values of Voltage magnitude and Voltage angle as the
> initial guess? In the case files for eg. 'case57' the Vm and Va are
> probably the final voltage magnitudes and voltage angles.
>
> Shouldn't it be like assigning all the voltage magnitudes of PQ bus as 1.0
> pu and voltage angles of all PV and PQ bus as 0 degree for a flat start.
>
> Depending on the answer of this question I would like to convey my other
> doubts/questions.
>
> Thanks in advance.
>
>
>
> *SAYANDEV GHOSH*
> Assistant Professor
> Electrical Engineering Department
> Chaibasa Engineering College, Chaibasa, Jharkhand
>