Source Code for Module pypower.makeBdc

 1  # Copyright (C) 1996-2011 Power System Engineering Research Center (PSERC) 
 2  # Copyright (C) 2011 Richard Lincoln 
 3  # 
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16   
17  """Builds the B matrices and phase shift injections for DC power flow. 
18  """ 
19   
20  from sys import stderr 
21   
22  from numpy import ones, r_, pi, flatnonzero as find 
23  from scipy.sparse import csr_matrix as sparse 
24   
25  from idx_bus import BUS_I 
26  from idx_brch import F_BUS, T_BUS, BR_X, TAP, SHIFT, BR_STATUS 
27   
28   
29 -def makeBdc(baseMVA, bus, branch): 
30      """Builds the B matrices and phase shift injections for DC power flow. 
31   
32      Returns the B matrices and phase shift injection vectors needed for a 
33      DC power flow. 
34      The bus real power injections are related to bus voltage angles by:: 
35          P = Bbus * Va + PBusinj 
36      The real power flows at the from end the lines are related to the bus 
37      voltage angles by:: 
38          Pf = Bf * Va + Pfinj 
39      Does appropriate conversions to p.u. 
40   
41      @see: L{dcpf} 
42   
43      @author: Carlos E. Murillo-Sanchez (PSERC Cornell & Universidad 
44      Autonoma de Manizales) 
45      @author: Ray Zimmerman (PSERC Cornell) 
46      @author: Richard Lincoln 
47      """ 
48      ## constants 
49      nb = bus.shape[0]          ## number of buses 
50      nl = branch.shape[0]       ## number of lines 
51   
52      ## check that bus numbers are equal to indices to bus (one set of bus nums) 
53      if any(bus[:, BUS_I] != range(nb)): 
54          stderr.write('makeBdc: buses must be numbered consecutively in ' 
55                       'bus matrix\n') 
56   
57      ## for each branch, compute the elements of the branch B matrix and the phase 
58      ## shift "quiescent" injections, where 
59      ## 
60      ##      | Pf |   | Bff  Bft |   | Vaf |   | Pfinj | 
61      ##      |    | = |          | * |     | + |       | 
62      ##      | Pt |   | Btf  Btt |   | Vat |   | Ptinj | 
63      ## 
64      stat = branch[:, BR_STATUS]               ## ones at in-service branches 
65      b = stat / branch[:, BR_X]                ## series susceptance 
66      tap = ones(nl)                            ## default tap ratio = 1 
67      i = find(branch[:, TAP])               ## indices of non-zero tap ratios 
68      tap[i] = branch[i, TAP]                   ## assign non-zero tap ratios 
69      b = b / tap 
70   
71      ## build connection matrix Cft = Cf - Ct for line and from - to buses 
72      f = branch[:, F_BUS]                           ## list of "from" buses 
73      t = branch[:, T_BUS]                           ## list of "to" buses 
74      i = r_[range(nl), range(nl)]                   ## double set of row indices 
75      ## connection matrix 
76      Cft = sparse((r_[ones(nl), -ones(nl)], (i, r_[f, t])), (nl, nb)) 
77   
78      ## build Bf such that Bf * Va is the vector of real branch powers injected 
79      ## at each branch's "from" bus 
80      Bf = sparse((r_[b, -b], (i, r_[f, t])))## = spdiags(b, 0, nl, nl) * Cft 
81   
82      ## build Bbus 
83      Bbus = Cft.T * Bf 
84   
85      ## build phase shift injection vectors 
86      Pfinj = b * (-branch[:, SHIFT] * pi / 180)  ## injected at the from bus ... 
87      # Ptinj = -Pfinj                            ## and extracted at the to bus 
88      Pbusinj = Cft.T * Pfinj                ## Pbusinj = Cf * Pfinj + Ct * Ptinj 
89   
90      return Bbus, Bf, Pbusinj, Pfinj 
91