praktikum-holons/src/holeg/power_flow/FlowCalculation.java

package holeg.power_flow;

public class FlowCalculation {
    public static FlowData calculate(AdmittanceMatrix admittanceMatrix, Bus[] buses, Line[] lines, ComplexNumber[] voltages) {
        FlowData result = new FlowData();

        // Current calculation I = U / R; R = 1 / Y => I = Y * U
        ComplexMatrix busCurrent = admittanceMatrix.multiply(voltages);

        // Calculate line currents
        ComplexMatrix lineCurrent = ComplexMatrix.sameSizeAs(admittanceMatrix);
        for (int i = 0; i < lines.length; i++) {
            Line line = lines[i];

            // Calculate current by multiplying the voltage dropped between the line and the admittance
            ComplexNumber voltageDrop = voltages[line.from].subtract(voltages[line.to]);
            ComplexNumber current = voltageDrop.multiply(admittanceMatrix.get(line.to, line.from));

            // Symmetrical
            lineCurrent.set(line.to, line.from, current.negate());
            lineCurrent.set(line.from, line.to, current);
        }

        // Power calculation (P = U * I)
        ComplexMatrix linePower = ComplexMatrix.sameSizeAs(lineCurrent);
        for (int i = 0; i < linePower.getWidth(); i++)
            for (int j = 0; j < linePower.getHeight(); j++)
                if (i != j)
                    linePower.set(i, j, voltages[i].multiply(lineCurrent.get(i, j).conjugate()));

        // Create result and calculate losses
        result.busCurrent = new double[buses.length];
        result.lineCurrent = new double[lines.length];
        result.busInjection = new ComplexNumber[buses.length];
        result.linePower = new ComplexNumber[lines.length];
        result.linePowerLoss = new ComplexNumber[lines.length];

        for (int i = 0; i < buses.length; i++) {
            result.busCurrent[i] = busCurrent.get(i, 0).len();

            // Power = Current * Voltage
            result.busInjection[i] = busCurrent.get(i, 0).conjugate().multiply(voltages[i]);
        }
        for (int i = 0; i < lines.length; i++) {
            Line line = lines[i];

            result.lineCurrent[i] = lineCurrent.get(line.from, line.to).len();
            result.linePower[i] = linePower.get(line.from, line.to).negate();
            result.linePowerLoss[i] = linePower.get(line.from, line.to).add(linePower.get(line.to, line.from));
        }

        return result;
    }
}