Connectivity Matrix

This section explains how to build a CSC connectivity matrix directly with no intermediate LIL matrix.

The connectivity matrix is as follows:

	Bus1	Bus2	Bus3	Bus4	Bus5
G1		1
G2			1
G3					1

This matrix in CSC format is:

indptr = [0, 0, 1, 2, 2, 3]

indices = [0, 1, 2]

data = [1, 1, 1]

The following code exemplifies the concept of building a CSC connectivity matrix directly.

import numpy as np
from CSparse3.csc import CscMat


# declare the Bus class
class Bus:
    def __init__(self, name, gen):
        self.name = name
        self.gen = gen


# declare the generator class
class Gen:
    def __init__(self, name, p=0):
        self.name = name
        self.p = p


# build the example
buses = [Bus('Bus1', []),
         Bus('Bus2', [Gen('G1', 10)]),
         Bus('Bus3', [Gen('G2', 20)]),
         Bus('Bus4', []),
         Bus('Bus5', [Gen('G3', 30)])]

# count the elements to declare the matrices
ng = 0
nb = len(buses)
for b in buses:
    ng += len(b.gen)

# declare the connectivity matrix
gen_conn = CscMat(ng, nb, nz_max=ng)
p = np.zeros(ng)
gi = 0  # this is the total generator counter
for i, b in enumerate(buses):
    for k, g in enumerate(b.gen):
        gen_conn.indices[gi] = gi  # store the row indices
        gen_conn.data[gi] = 1  # set the value
        p[gi] = g.p
        gi += 1

    gen_conn.indptr[i + 1] = gi  # store the column pointer when the bus changes

gen_conn.indptr[nb] = gi  # store the last column pointer

print('Generator-Bus connectivity matrix')
print(gen_conn.todense())

print('indptr = ', gen_conn.indptr)
print('indices = ', gen_conn.indices)
print('data = ', gen_conn.data)

print('Bus power injections')
print(gen_conn.t() * p)

The output is the following:

Generator-Bus connectivity matrix
[[0. 1. 0. 0. 0.]
 [0. 0. 1. 0. 0.]
 [0. 0. 0. 0. 1.]]

indptr = [0 0 1 2 2 3]

indices = [0 1 2]

data = [1. 1. 1.]

Bus power injections
[ 0. 10. 20.  0. 30.]