hello everyone I have encountered a problem running NEWTON RAPHSON load flow code in 69 bus system.

Index in position 1 is invalid. Array indices must be positive integers or logical values.

Error in LFNEWTON69 (line 18)
       Ybus(nl(k),nr(k))=Ybus(nl(k),nr(k))-y(k)/a(k);

and also with some line and bus data I get the error that the code cannot be converged.

can anyone help me with the code and 69 bus system data?

[Walter Roberson]

Are you certain that k is a positive integer, and that nl(k) and nr(k) are positive integers?

[Amir Hosseini]

my first matrix indices is 0 which is true according to IEEE network data but the Ybus matrix formation needs to have positive integers and I don't know how to change the datas.

[Amir Hosseini]

[0	1
1	2
2	3
3	4
4	5
5	6
6	7
7	8
8	9
9	10
10	11
11	12
12	13
13	14
14	15
15	16
16	17
17	18
18	19
19	20
20	21
21	22
22	23
23	24
24	25
25	26
26	27
3	28
28	29
29	30
30	31
31	32
32	33
33	34
34	35
4	36
36	37
37	38
38	39
8	40
40	41
9	42
42	43
43	44
44	45
45	46
46	47
47	48
48	49
49	50
50	51
51	52
52	53
53	54
11	55
55	56
12	57
57	58
3	59
59	60
60	61
61	62
62	63
63	64
64	65
65	66
66	67
67	68
68	69];

line datas are as above according to IEEE network data and also my nl = linedata(:,1); nr = linedata(:,2);

[Walter Roberson]

The first entry there is 0, which is not a positive integer and so cannot be used as a subscript.

If the numbering starts at 0 then

nl = linedata(:,1)+1; nr = linedata(:,2)+1;

[Amir Hosseini]

then the error will be

Index exceeds the number of array elements (69).

which is true because n1 and nbr should nor exceed 69.

[Walter Roberson]

Well, you have defined nl = linedata(:,1) and the first entry linedata(1,1) is 0, and you want to use nl as an index, which is going to result in 0 being used as an index. What are you hoping to have happen in that situation ?

[Amir Hosseini]

I guess my datas might be incorrect and need new one with .mat format and neet file exchange!

[Walter Roberson]

Perhaps you need to start your k loop from 2 ?

[Amir Hosseini]

then it won't be converged again and that's the error:

Warning: Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN.