Home > matpower7.0 > extras > se > doSE.m

doSE

PURPOSE ^

DOSE Do state estimation.

SYNOPSIS ^

function [V, converged, iterNum, z, z_est, error_sqrsum] = doSE(baseMVA, bus, gen, branch, Ybus, Yf, Yt, V0, ref, pv, pq, measure, idx, sigma)

DESCRIPTION ^

DOSE  Do state estimation.
   created by Rui Bo on 2007/11/12

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

0001 function [V, converged, iterNum, z, z_est, error_sqrsum] = doSE(baseMVA, bus, gen, branch, Ybus, Yf, Yt, V0, ref, pv, pq, measure, idx, sigma)
0002 %DOSE  Do state estimation.
0003 %   created by Rui Bo on 2007/11/12
0004 
0005 %   MATPOWER
0006 %   Copyright (c) 1996-2016, Power Systems Engineering Research Center (PSERC)
0007 %   by Rui Bo
0008 %   and Ray Zimmerman, PSERC Cornell
0009 %
0010 %   This file is part of MATPOWER/mx-se.
0011 %   Covered by the 3-clause BSD License (see LICENSE file for details).
0012 %   See https://github.com/MATPOWER/mx-se/ for more info.
0013 
0014 %% define named indices into bus, gen, branch matrices
0015 [PQ, PV, REF, NONE, BUS_I, BUS_TYPE, PD, QD, GS, BS, BUS_AREA, VM, ...
0016     VA, BASE_KV, ZONE, VMAX, VMIN, LAM_P, LAM_Q, MU_VMAX, MU_VMIN] = idx_bus;
0017 [F_BUS, T_BUS, BR_R, BR_X, BR_B, RATE_A, RATE_B, ...
0018     RATE_C, TAP, SHIFT, BR_STATUS, PF, QF, PT, QT, MU_SF, MU_ST] = idx_brch;
0019 [GEN_BUS, PG, QG, QMAX, QMIN, VG, MBASE, ...
0020     GEN_STATUS, PMAX, PMIN, MU_PMAX, MU_PMIN, MU_QMAX, MU_QMIN] = idx_gen;
0021 
0022 %% options
0023 tol     = 1e-5; % mpopt.pf.tol;
0024 max_it  = 100;  % mpopt.pf.nr.max_it;
0025 verbose = 0;
0026 
0027 %% initialize
0028 converged = 0;
0029 i = 0;
0030 V = V0;
0031 Va = angle(V);
0032 Vm = abs(V);
0033 
0034 nb = size(Ybus, 1);
0035 f = branch(:, F_BUS);       %% list of "from" buses
0036 t = branch(:, T_BUS);       %% list of "to" buses
0037 
0038 %% get non reference buses
0039 nonref = [pv;pq];
0040 
0041 %% form measurement vector 'z'. NOTE: all are p.u. values
0042 z = [
0043     measure.PF
0044     measure.PT
0045     measure.PG
0046     measure.Va
0047     measure.QF
0048     measure.QT
0049     measure.QG
0050     measure.Vm
0051     ];
0052 
0053 %% form measurement index vectors
0054 idx_zPF = idx.idx_zPF;
0055 idx_zPT = idx.idx_zPT;
0056 idx_zPG = idx.idx_zPG;
0057 idx_zVa = idx.idx_zVa;
0058 idx_zQF = idx.idx_zQF;
0059 idx_zQT = idx.idx_zQT;
0060 idx_zQG = idx.idx_zQG;
0061 idx_zVm = idx.idx_zVm;
0062 
0063 %% get R inverse matrix
0064 sigma_vector = [
0065     sigma.sigma_PF*ones(size(idx_zPF, 1), 1)
0066     sigma.sigma_PT*ones(size(idx_zPT, 1), 1)
0067     sigma.sigma_PG*ones(size(idx_zPG, 1), 1)
0068     sigma.sigma_Va*ones(size(idx_zVa, 1), 1)
0069     sigma.sigma_QF*ones(size(idx_zQF, 1), 1)
0070     sigma.sigma_QT*ones(size(idx_zQT, 1), 1)
0071     sigma.sigma_QG*ones(size(idx_zQG, 1), 1)
0072     sigma.sigma_Vm*ones(size(idx_zVm, 1), 1)
0073     ]; % NOTE: zero-valued elements of simga are skipped
0074 sigma_square = sigma_vector.^2;
0075 R_inv = diag(1./sigma_square);
0076 
0077 %% do Newton iterations
0078 while (~converged & i < max_it)
0079     %% update iteration counter
0080     i = i + 1;
0081     
0082     %% --- compute estimated measurement ---
0083     Sfe = V(f) .* conj(Yf * V);
0084     Ste = V(t) .* conj(Yt * V);
0085     %% compute net injection at generator buses
0086     gbus = gen(:, GEN_BUS);
0087     Sgbus = V(gbus) .* conj(Ybus(gbus, :) * V);
0088     Sgen = Sgbus * baseMVA + (bus(gbus, PD) + 1j*bus(gbus, QD));    %% inj S + local Sd
0089     Sgen = Sgen/baseMVA;
0090     z_est = [ % NOTE: all are p.u. values
0091         real(Sfe(idx_zPF));
0092         real(Ste(idx_zPT));
0093         real(Sgen(idx_zPG));
0094         angle(V(idx_zVa));
0095         imag(Sfe(idx_zQF));
0096         imag(Ste(idx_zQT));
0097         imag(Sgen(idx_zQG));
0098         abs(V(idx_zVm));
0099     ];
0100 
0101     %% --- get H matrix ---
0102     [dSbus_dVa, dSbus_dVm] = dSbus_dV(Ybus, V);
0103     [dSf_dVa, dSf_dVm, dSt_dVa, dSt_dVm, Sf, St] = dSbr_dV(branch, Yf, Yt, V);
0104 %     genbus_row = findBusRowByIdx(bus, gbus);
0105     genbus_row = gbus;  %% rdz, this should be fine if using internal bus numbering
0106 
0107     %% get sub-matrix of H relating to line flow
0108     dPF_dVa = real(dSf_dVa); % from end
0109     dQF_dVa = imag(dSf_dVa);   
0110     dPF_dVm = real(dSf_dVm);
0111     dQF_dVm = imag(dSf_dVm);
0112     dPT_dVa = real(dSt_dVa);% to end
0113     dQT_dVa = imag(dSt_dVa);   
0114     dPT_dVm = real(dSt_dVm);
0115     dQT_dVm = imag(dSt_dVm);   
0116     %% get sub-matrix of H relating to generator output
0117     dPG_dVa = real(dSbus_dVa(genbus_row, :));
0118     dQG_dVa = imag(dSbus_dVa(genbus_row, :));
0119     dPG_dVm = real(dSbus_dVm(genbus_row, :));
0120     dQG_dVm = imag(dSbus_dVm(genbus_row, :));
0121     %% get sub-matrix of H relating to voltage angle
0122     dVa_dVa = eye(nb);
0123     dVa_dVm = zeros(nb, nb);
0124     %% get sub-matrix of H relating to voltage magnitude
0125     dVm_dVa = zeros(nb, nb);
0126     dVm_dVm = eye(nb);
0127     H = [
0128         dPF_dVa(idx_zPF, nonref)   dPF_dVm(idx_zPF, nonref);
0129         dPT_dVa(idx_zPT, nonref)   dPT_dVm(idx_zPT, nonref);
0130         dPG_dVa(idx_zPG, nonref)   dPG_dVm(idx_zPG, nonref);
0131         dVa_dVa(idx_zVa, nonref)   dVa_dVm(idx_zVa, nonref);
0132         dQF_dVa(idx_zQF, nonref)   dQF_dVm(idx_zQF, nonref);
0133         dQT_dVa(idx_zQT, nonref)   dQT_dVm(idx_zQT, nonref);
0134         dQG_dVa(idx_zQG, nonref)   dQG_dVm(idx_zQG, nonref);
0135         dVm_dVa(idx_zVm, nonref)   dVm_dVm(idx_zVm, nonref);
0136         ];
0137     
0138     %% compute update step
0139     J = H'*R_inv*H;
0140     F = H'*R_inv*(z-z_est); % evalute F(x)
0141     if ~isobservable(H, pv, pq)
0142         error('doSE: system is not observable');
0143     end
0144     dx = (J \ F);
0145 
0146     %% check for convergence
0147     normF = norm(F, inf);
0148     if verbose > 1
0149         fprintf('\niteration [%3d]\t\tnorm of mismatch: %10.3e', i, normF);
0150     end
0151     if normF < tol
0152         converged = 1;
0153     end
0154     
0155     %% update voltage
0156     Va(nonref) = Va(nonref) + dx(1:size(nonref, 1));
0157     Vm(nonref) = Vm(nonref) + dx(size(nonref, 1)+1:2*size(nonref, 1));
0158     V = Vm .* exp(1j * Va); % NOTE: angle is in radians in pf solver, but in degree in case data
0159     Vm = abs(V);            %% update Vm and Va again in case
0160     Va = angle(V);          %% we wrapped around with a negative Vm
0161 end
0162 
0163 iterNum = i;
0164 
0165 %% get weighted sum of squared errors
0166 error_sqrsum = sum((z - z_est).^2./sigma_square);
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