POLYCOST Evaluates polynomial generator cost & derivatives. F = POLYCOST(GENCOST, PG) returns the vector of costs evaluated at PG DF = POLYCOST(GENCOST, PG, 1) returns the vector of first derivatives of costs evaluated at PG D2F = POLYCOST(GENCOST, PG, 2) returns the vector of second derivatives of costs evaluated at PG GENCOST must contain only polynomial costs PG is in MW, not p.u. (works for QG too) This is a more effecient implementation that what can be done with MATLAB's built-in POLYVAL and POLYDER functions.
0001 function f = polycost(gencost, Pg, der) 0002 %POLYCOST Evaluates polynomial generator cost & derivatives. 0003 % F = POLYCOST(GENCOST, PG) returns the vector of costs evaluated at PG 0004 % 0005 % DF = POLYCOST(GENCOST, PG, 1) returns the vector of first derivatives 0006 % of costs evaluated at PG 0007 % 0008 % D2F = POLYCOST(GENCOST, PG, 2) returns the vector of second derivatives 0009 % of costs evaluated at PG 0010 % 0011 % GENCOST must contain only polynomial costs 0012 % PG is in MW, not p.u. (works for QG too) 0013 % 0014 % This is a more effecient implementation that what can be done with 0015 % MATLAB's built-in POLYVAL and POLYDER functions. 0016 0017 % MATPOWER 0018 % $Id: polycost.m 1635 2010-04-26 19:45:26Z ray $ 0019 % by Ray Zimmerman, PSERC Cornell 0020 % Copyright (c) 2009-2010 by Power System Engineering Research Center (PSERC) 0021 % 0022 % This file is part of MATPOWER. 0023 % See http://www.pserc.cornell.edu/matpower/ for more info. 0024 % 0025 % MATPOWER is free software: you can redistribute it and/or modify 0026 % it under the terms of the GNU General Public License as published 0027 % by the Free Software Foundation, either version 3 of the License, 0028 % or (at your option) any later version. 0029 % 0030 % MATPOWER is distributed in the hope that it will be useful, 0031 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0032 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0033 % GNU General Public License for more details. 0034 % 0035 % You should have received a copy of the GNU General Public License 0036 % along with MATPOWER. If not, see <http://www.gnu.org/licenses/>. 0037 % 0038 % Additional permission under GNU GPL version 3 section 7 0039 % 0040 % If you modify MATPOWER, or any covered work, to interface with 0041 % other modules (such as MATLAB code and MEX-files) available in a 0042 % MATLAB(R) or comparable environment containing parts covered 0043 % under other licensing terms, the licensors of MATPOWER grant 0044 % you additional permission to convey the resulting work. 0045 0046 %%----- initialize ----- 0047 %% define named indices into data matrices 0048 [PW_LINEAR, POLYNOMIAL, MODEL, STARTUP, SHUTDOWN, NCOST, COST] = idx_cost; 0049 0050 if nargin < 3 0051 der = 0; 0052 end 0053 0054 if any(gencost(:, MODEL) == PW_LINEAR) 0055 error('polycost: all costs must be polynomial'); 0056 end 0057 0058 ng = length(Pg); 0059 maxN = max(gencost(:, NCOST)); 0060 minN = min(gencost(:, NCOST)); 0061 0062 %% form coefficient matrix where 1st column is constant term, 2nd linear, etc. 0063 c = zeros(ng, maxN); 0064 for n = minN:maxN 0065 k = find(gencost(:, NCOST) == n); %% cost with n coefficients 0066 c(k, 1:n) = gencost(k, (COST+n-1):-1:COST); 0067 end 0068 0069 %% do derivatives 0070 for d = 1:der 0071 if size(c, 2) >= 2 0072 c = c(:, 2:maxN-d+1); 0073 else 0074 c = zeros(ng, 1); 0075 break; 0076 end 0077 for k = 2:maxN-d 0078 c(:, k) = k * c(:, k); 0079 end 0080 end 0081 0082 %% evaluate polynomial 0083 if isempty(c) 0084 f = zeros(size(Pg)); 0085 else 0086 f = c(:, 1); %% constant term 0087 for k = 2:size(c, 2) 0088 f = f + c(:, k) .* Pg .^ (k-1); 0089 end 0090 end