Qlim.C

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/*
 * Copyright (c) 2024 Saud Zahir
 *
 * This file is part of deltaFlow.
 *
 * deltaFlow is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * deltaFlow is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with deltaFlow.  If not, see
 * <https://www.gnu.org/licenses/>.
 */
 
#include <cmath>
#include <limits>
#include <vector>
 
#include "Qlim.H"
#include "Logger.H"
#include "Data.H"
 
bool checkQlimits(
    const Eigen::VectorXd& V,
    const Eigen::VectorXd& delta,
    Eigen::VectorXi& type_bus,
    const Eigen::MatrixXd& G,
    const Eigen::MatrixXd& B,
    BusData& busData,
    const std::vector<int>& pv_bus_id,
    int n_bus
) {
    // Q-limits: zero means no limit, using +/-inf
    Eigen::VectorXd Qmax = busData.Qgmax;
    Eigen::VectorXd Qmin = busData.Qgmin;
 
    for (int i = 0; i < n_bus; ++i) {
        if (Qmax(i) == 0.0) Qmax(i) = std::numeric_limits<double>::infinity();
        if (Qmin(i) == 0.0) Qmin(i) = -std::numeric_limits<double>::infinity();
    }
 
    // Compute reactive power Q at each bus with converged V and delta
    Eigen::VectorXd Q = Eigen::VectorXd::Zero(n_bus);
    for (int i = 0; i < n_bus; ++i) {
        for (int j = 0; j < n_bus; ++j) {
            double dij = delta(i) - delta(j);
            Q(i) += V(i) * V(j) * (G(i, j) * std::sin(dij) - B(i, j) * std::cos(dij));
        }
    }
 
    // Qg = Q_calc + Ql (all in p.u.)
    Eigen::VectorXd Qg = Q + busData.Ql;
 
    // Check Q-limits only for PV buses
    bool qlim_hit = false;
 
    for (int idx : pv_bus_id) {
        if (Qg(idx) > Qmax(idx)) {
            type_bus(idx) = 3;  // PV to PQ
            busData.Qg(idx) = Qmax(idx);  // Fix Q at limit for next solver run
            qlim_hit = true;
            LOG_DEBUG("Q-limit (max) hit at bus {} : Qg = {:.4f} > Qmax = {:.4f}", idx + 1, Qg(idx), Qmax(idx));
        } else if (Qg(idx) < Qmin(idx)) {
            type_bus(idx) = 3;  // PV to PQ
            busData.Qg(idx) = Qmin(idx);  // Fix Q at limit for next solver run
            qlim_hit = true;
            LOG_DEBUG("Q-limit (min) hit at bus {} : Qg = {:.4f} < Qmin = {:.4f}", idx + 1, Qg(idx), Qmin(idx));
        }
    }
 
    if (!qlim_hit) {
        LOG_DEBUG("Power flow converged without hitting Q-limits.");
    }
 
    return qlim_hit;
}