POLY2PWL Converts polynomial cost variable to piecewise linear. PWLCOST = POLY2PWL(POLYCOST, PMIN, PMAX, NPTS) converts the polynomial cost variable POLYCOST into a piece-wise linear cost by evaluating at zero and then at NPTS evenly spaced points between PMIN and PMAX. If PMIN <= 0 (such as for reactive power, where P really means Q) it just uses NPTS evenly spaced points between PMIN and PMAX.
0001 function pwlcost = poly2pwl(polycost, Pmin, Pmax, npts) 0002 %POLY2PWL Converts polynomial cost variable to piecewise linear. 0003 % PWLCOST = POLY2PWL(POLYCOST, PMIN, PMAX, NPTS) converts the polynomial 0004 % cost variable POLYCOST into a piece-wise linear cost by evaluating at 0005 % zero and then at NPTS evenly spaced points between PMIN and PMAX. If 0006 % PMIN <= 0 (such as for reactive power, where P really means Q) it just 0007 % uses NPTS evenly spaced points between PMIN and PMAX. 0008 0009 % MATPOWER 0010 % $Id: poly2pwl.m 1635 2010-04-26 19:45:26Z ray $ 0011 % by Ray Zimmerman, PSERC Cornell 0012 % Copyright (c) 1996-2010 by Power System Engineering Research Center (PSERC) 0013 % 0014 % This file is part of MATPOWER. 0015 % See http://www.pserc.cornell.edu/matpower/ for more info. 0016 % 0017 % MATPOWER is free software: you can redistribute it and/or modify 0018 % it under the terms of the GNU General Public License as published 0019 % by the Free Software Foundation, either version 3 of the License, 0020 % or (at your option) any later version. 0021 % 0022 % MATPOWER is distributed in the hope that it will be useful, 0023 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0024 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0025 % GNU General Public License for more details. 0026 % 0027 % You should have received a copy of the GNU General Public License 0028 % along with MATPOWER. If not, see <http://www.gnu.org/licenses/>. 0029 % 0030 % Additional permission under GNU GPL version 3 section 7 0031 % 0032 % If you modify MATPOWER, or any covered work, to interface with 0033 % other modules (such as MATLAB code and MEX-files) available in a 0034 % MATLAB(R) or comparable environment containing parts covered 0035 % under other licensing terms, the licensors of MATPOWER grant 0036 % you additional permission to convey the resulting work. 0037 0038 [PW_LINEAR, POLYNOMIAL, MODEL, STARTUP, SHUTDOWN, NCOST, COST] = idx_cost; 0039 0040 pwlcost = polycost; 0041 [m, n] = size(polycost); %% size of piece being changed 0042 pwlcost(:, MODEL) = PW_LINEAR * ones(m, 1); %% change cost model 0043 pwlcost(:, COST:n) = zeros(size(pwlcost(:, COST:n))); %% zero out old data 0044 pwlcost(:, NCOST) = npts * ones(m, 1); %% change number of data points 0045 0046 for i = 1:m 0047 if Pmin(i) == 0 0048 step = (Pmax(i) - Pmin(i)) / (npts - 1); 0049 xx = (Pmin(i):step:Pmax(i)); 0050 elseif Pmin(i) > 0 0051 step = (Pmax(i) - Pmin(i)) / (npts - 2); 0052 xx = [0 Pmin(i):step:Pmax(i)]; 0053 elseif Pmin(i) < 0 && Pmax(i) > 0 %% for when P really means Q 0054 step = (Pmax(i) - Pmin(i)) / (npts - 1); 0055 xx = (Pmin(i):step:Pmax(i)); 0056 end 0057 yy = totcost(polycost(i, :), xx); 0058 pwlcost(i, COST:2:(COST + 2*(npts-1) )) = xx; 0059 pwlcost(i, (COST+1):2:(COST + 2*(npts-1) + 1)) = yy; 0060 end