margcost

MARGCOST    Computes marginal cost for generators at given output level.
   MARGINALCOST = MARGCOST(GENCOST, PG) computes marginal cost for generators
   given a matrix in gencost format and a column vector of generation levels.
   The return value has the same dimensions as PG. Each row of GENCOST is
   used to evaluate the cost at the points specified in the corresponding row
   of PG.

0001 function marginalcost = margcost(gencost, Pg)
0002 %MARGCOST    Computes marginal cost for generators at given output level.
0003 %   MARGINALCOST = MARGCOST(GENCOST, PG) computes marginal cost for generators
0004 %   given a matrix in gencost format and a column vector of generation levels.
0005 %   The return value has the same dimensions as PG. Each row of GENCOST is
0006 %   used to evaluate the cost at the points specified in the corresponding row
0007 %   of PG.
0008 
0009 %   MATPOWER
0010 %   Copyright (c) 1996-2015 by Power System Engineering Research Center (PSERC)
0011 %   by Ray Zimmerman, PSERC Cornell
0012 %   & Carlos E. Murillo-Sanchez, PSERC Cornell & Universidad Autonoma de Manizales
0013 %
0014 %   $Id: margcost.m 2644 2015-03-11 19:34:22Z ray $
0015 %
0016 %   This file is part of MATPOWER.
0017 %   Covered by the 3-clause BSD License (see LICENSE file for details).
0018 %   See http://www.pserc.cornell.edu/matpower/ for more info.
0019 
0020 [PW_LINEAR, POLYNOMIAL, MODEL, STARTUP, SHUTDOWN, NCOST, COST] = idx_cost;
0021 
0022 [ng, m] = size(gencost);
0023 marginalcost = zeros(ng, 1);
0024 
0025 if ~isempty(gencost)
0026   ipwl = find(gencost(:, MODEL) == PW_LINEAR);
0027   ipol = find(gencost(:, MODEL) == POLYNOMIAL);
0028   if ~isempty(ipwl)
0029     x = gencost(:, COST:2:(m-1));
0030     y = gencost(:, (COST+1):2:m);
0031     for i = ipwl'
0032       if gencost(i, NCOST) > 0
0033         c = diff(y(i,:)) ./ diff(x(i,:));
0034         k = find(Pg(i,:) <= x(i,:), 1);
0035         if isempty(k)
0036           marginalcost(i,:) = c(end);
0037         elseif k == 1
0038           marginalcost(i,:) = c(1);
0039         else
0040           marginalcost(i,:) = c(k-1);
0041         end
0042       end
0043     end
0044   end
0045   for i = ipol'
0046     marginalcost(i,:) = polyval(polyder(gencost(i, COST:(COST+gencost(i, NCOST)-1) )), Pg(i,:) );
0047   end
0048 end