mirror of
https://git.rwth-aachen.de/acs/public/villas/node/
synced 2025-03-16 00:00:02 +01:00
364 lines
11 KiB
C++
364 lines
11 KiB
C++
/* ipDFT PMU hook.
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*
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* Author: Andres Acosta <andres.acosta@eonerc.rwth-aachen.de>
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* SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <villas/hooks/pmu.hpp>
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namespace villas {
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namespace node {
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class TruncatedIpDftPmuHook : public PmuHook {
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protected:
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std::complex<double> omega;
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std::vector<std::vector<double>> twf_dft_r;
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std::vector<std::vector<double>> twf_dft_i;
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unsigned P;
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unsigned startBin;
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unsigned frequencyCount; // Number of requency bins that are calculated
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double estimationRange; // The range around nominalFreq used for estimation
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struct Complex {
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double r;
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double i;
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double mag;
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double ph;
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double f;
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};
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struct PhasorReIm {
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double r;
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double i;
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};
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std::vector<Complex> Xk;
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public:
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TruncatedIpDftPmuHook(Path *p, Node *n, int fl, int prio, bool en = true)
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: PmuHook(p, n, fl, prio, en), P(1), frequencyCount(0), estimationRange(0)
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{}
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PhasorReIm hann_frt(double k, unsigned M) {
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PhasorReIm val;
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double m = M_PI / M;
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double a = 0.5 * sin(M_PI * k) / sin(k * M);
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double b = 0.25 * sin(M_PI * (k+1)) / sin((k+1) * m);
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double c = 0.25 * sin(M_PI * (k-1)) / sin((k-1) * m);
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val.r = cos(k*(M-1)*m) * a - cos((k+1)*(M-1)*m) * b - cos((k-1)*(M-1)*m) * c;
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val.i = -sin(k*(M-1)*m) * a + sin((k+1)*(M-1)*m) * b + sin((k-1)*(M-1)*m) * c;
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return val;
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}
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void prepare() {
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PmuHook::prepare();
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// This is assuming that the window size (in number of samples) covers a period of the signal
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// const double frequencyResolution = nominalFreq;
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// Number of samples per frame consider minimum Fres<f0/2. Samples per reported phasor
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// windowSize = sampleRate / frequencyResolution;
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// Time window per frame (ms)
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// const double Tw = 1000 / phasorRate;
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// Number of frequency bins given the frequency resolution: Fres=Nr=Fs/Nc
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if (phasorRate < 5) {
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frequencyCount = 16;
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} else {
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frequencyCount = (nominalFreq / phasorRate) + 2;
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}
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if (frequencyCount%2 == 1) {
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frequencyCount = frequencyCount + 1;
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}
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// Initialize matrix of dft coeffients
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startBin = (unsigned)floor(nominalFreq/phasorRate - frequencyCount/2);
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// unsigned endBin = startBin + frequencyCount;
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twf_dft_r.clear();
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twf_dft_i.clear();
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// twf_dft_r.reserve(windowSize*frequencyCount);
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// twf_dft_i.reserve(windowSize*frequencyCount);
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for (unsigned k = 0; k < frequencyCount; k++) {
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twf_dft_r.emplace_back(windowSize, 0.0);
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twf_dft_i.emplace_back(windowSize, 0.0);
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}
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const double dw = 2* M_PI / frequencyCount;
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// twiddle factor for truncated DFT
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for (unsigned k = 0; k < frequencyCount; k++) {
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for (unsigned n = 0; n < windowSize; n++) {
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twf_dft_r[k][n] = cos(n*(k+startBin+1)*dw);
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twf_dft_i[k][n] = sin(n*(k+startBin+1)*dw);
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}
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Xk.push_back({0., 0., 0., 0., 0.});
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}
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}
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void parse(json_t *json) {
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PmuHook::parse(json);
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int ret;
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json_error_t err;
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assert(state != State::STARTED);
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Hook::parse(json);
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ret = json_unpack_ex(json, &err, 0, "{ s?: F}", "estimation_range",
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&estimationRange);
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if (ret)
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throw ConfigError(json, err, "node-config-hook-ip-dft-pmu");
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if (estimationRange <= 0)
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throw ConfigError(
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json, "node-config-hook-ip-dft-pmu-estimation_range",
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"Estimation range cannot be less or equal than 0 tried to set {}",
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estimationRange);
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}
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PmuHook::Phasor estimatePhasor(dsp::CosineWindow<double> *window,
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PmuHook::Phasor lastPhasor) {
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PmuHook::Phasor estimatedPhasor = {0};
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const double B = 0.5*frequencyCount; // Integration of wh over the whole window
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const double b = 1/B;
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int km = 0;
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double dfold = 0.0; // last df/dt of frequency
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double df = 0.0; // df/dt of frequency
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double d2fold = 0.0; // last d2f/dt2 of frequency
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double d2f = 0.0; // d2f/dt2 of frequency
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double rocof = 0.0; // ROCOF
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double fold = 0.0; // last frequency value
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double f = 0.0; // current frequency value
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double state_rocof = false; // TRUE for Dynamic, False for Static State
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for (unsigned n = 0; n < windowSize; n++) {
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for (unsigned k = 0; k < frequencyCount; k++) {
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// Real part of X[k]
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Xk[k].r += (*window).val(n) * twf_dft_r[k][n];
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// Imaginary part of X[k]
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Xk[k].i -= (*window).val(n) * twf_dft_i[k][n];
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}
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}
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for (unsigned k = 0; k < frequencyCount; k++) {
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Xk[k].r *= b;
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Xk[k].i *= b;
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Xk[k].mag = pow(Xk[k].r*Xk[k].r + Xk[k].i*Xk[k].i, 0.5);
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if (Xk[k].mag > Xk[km].mag) {
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km = k;
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}
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}
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std::vector<Complex> wXk = Xk;
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// Windowing in Frequency Domain
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for (unsigned k = 1; k < frequencyCount-1; k++) {
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wXk[k].r = -0.25*Xk[k-1].r + 0.50*Xk[k].r - 0.25*Xk[k+1].r;
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wXk[k].i = -0.25*Xk[k-1].i + 0.50*Xk[k].i - 0.25*Xk[k+1].i;
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wXk[k].mag = pow(wXk[k].r*wXk[k].r + wXk[k].i*wXk[k].i, 0.5);
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}
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Xk = wXk;
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int epsil = (Xk[km+1].mag > Xk[km-1].mag) ? 1 : -1;
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double alpha = std::abs(Xk[km].mag / Xk[km+epsil].mag);
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double delta = epsil * ((2 - alpha) / (1 + alpha));
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double a;
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if (delta < 0.00001) {
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a = 2.0;
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} else {
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a = 2 * M_PI * delta * (1 - pow(delta, 2)) / sin(M_PI * delta);
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}
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// i_ipDFT starts here
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/*i_ipDFT works well for higher reporting rates i.e. also Nr=25, but
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e_ipDFT outperforms i_ipDFT for lower reporting rates (e.g. Nr=10)
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i_ipDFT (variables definition) starts here*/
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PhasorReIm phasor;
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if (phasorRate > 10) {
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phasor.r = Xk[km].r;
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phasor.i = Xk[km].i;
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PhasorReIm phasor_epsil = phasor;
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PhasorReIm Xneg = phasor;
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PhasorReIm Xneg_epsil = phasor;
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phasor_epsil.r = Xk[km+epsil].r;
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phasor_epsil.i = Xk[km+epsil].i;
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double delta_old = delta;
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// i_ipDFT
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for (unsigned q = 0; q < P; q++) {
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PhasorReIm hann_ft = hann_frt(delta + 2*(km+startBin-1), windowSize);
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Xneg.r = 0.5*(phasor.r*hann_ft.r + phasor.i*hann_ft.i)*b;
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Xneg.i = 0.5*(phasor.r*hann_ft.i - phasor.i*hann_ft.r)*b;
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hann_ft = hann_frt(delta + epsil + 2*(km+startBin-1), windowSize);
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Xneg_epsil.r = 0.5*(phasor.r*hann_ft.r + phasor.i*hann_ft.i)*b;
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Xneg_epsil.i = 0.5*(phasor.r*hann_ft.i - phasor.i*hann_ft.r)*b;
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phasor.r = phasor.r-Xneg.r;
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phasor.i = phasor.i-Xneg.i;
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phasor_epsil.r = phasor_epsil.r - Xneg_epsil.r;
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phasor_epsil.i = phasor_epsil.i - Xneg_epsil.i;
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Xk[km].mag = pow(pow(phasor.r, 2) + pow(phasor.i, 2), 0.5);
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Xk[km+epsil].mag = pow(pow(phasor_epsil.r, 2) + pow(phasor_epsil.i, 2), 0.5);
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alpha = abs(Xk[km].mag / Xk[km+epsil].mag);
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delta = epsil*(2-alpha) / (1+alpha);
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if (abs(delta - delta_old)==0){
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q = P+1;
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}
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}
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} else {
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// end of i_ipDFT
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/*e_ipDFT
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e_ipDFT is very good from Nr=10 and Fs=10k; Not good otherwise.
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Nonetheless, for Nr>=10 it presents better precision than i_ipDFT
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*/
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phasor.r = Xk[km].r;
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phasor.i = Xk[km].i;
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PhasorReIm v_ipdft;
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v_ipdft.r = a*(Xk[km].r*cos(M_PI*delta)+Xk[km].i*sin(M_PI*delta));
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v_ipdft.i = a*(-Xk[km].r*sin(M_PI*delta)+Xk[km].i*cos(M_PI*delta));
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// This part is iterated P times
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// variables allocation
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PhasorReIm v1;
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v1.r = v_ipdft.r;
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v1.i = v_ipdft.i;
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double e_delta_corr = delta;
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std::vector<PhasorReIm> e_ipdft_3max;
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for (unsigned k = 0; k < 3; k++) {
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e_ipdft_3max.push_back({0., 0.});
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e_ipdft_3max[k] = phasor;
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}
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e_ipdft_3max[0].r = Xk[km-1].r;
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e_ipdft_3max[0].i = Xk[km-1].i;
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e_ipdft_3max[1].r = Xk[km].r;
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e_ipdft_3max[1].i = Xk[km].i;
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e_ipdft_3max[2].r = Xk[km+1].r;
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e_ipdft_3max[2].i = Xk[km+1].i;
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std::vector<double> e_ipdft_3mag;
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for (unsigned k = 0; k < 3; k++) {
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e_ipdft_3mag.push_back(0.);
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e_ipdft_3mag[k] = phasor.r;
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}
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PhasorReIm v_e_ipdft_max = phasor;
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double e_a = phasor.r;
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PhasorReIm hann_ft = phasor;
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std::vector<PhasorReIm> e_ipdft_3max_new;
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for (unsigned k = 0; k < 3; k++) {
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e_ipdft_3max_new.push_back({0., 0.});
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e_ipdft_3max_new[k] = phasor;
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}
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if (abs(delta) > 0) {
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for (unsigned q = 0; q < P; q++) {
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for (unsigned j = 0; j < 3; j++) {
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hann_ft = hann_frt(j-2+e_delta_corr+2*(km+startBin), windowSize);
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e_ipdft_3max_new[j].r = e_ipdft_3max[j].r-(v1.r*hann_ft.r + v1.i*hann_ft.i)*b;
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e_ipdft_3max_new[j].i = e_ipdft_3max[j].i+(v1.i*hann_ft.r - v1.r*hann_ft.i)*b;
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e_ipdft_3mag[j] = pow(pow(e_ipdft_3max_new[j].r, 2) + pow(e_ipdft_3max_new[j].i, 2), 0.5);
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}
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// interpolating the three bins to get the fractional correction term "delta_corr"
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e_delta_corr = 2*epsil*(abs(e_ipdft_3mag[2]-e_ipdft_3mag[0]))/(e_ipdft_3mag[1]*2 + e_ipdft_3mag[0]+ e_ipdft_3mag[2]);
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v_e_ipdft_max = e_ipdft_3max_new[1];
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if (abs(e_delta_corr)<0.00001) {
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e_delta_corr = 0;
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v1.r = v_e_ipdft_max.r;
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v1.i = v_e_ipdft_max.i;
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q = P+1;
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} else {
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e_a = (1-pow(e_delta_corr, 2))*abs((M_PI*e_delta_corr)/sin(M_PI*e_delta_corr));
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v1.r = e_a*(v_e_ipdft_max.r*cos(M_PI*e_delta_corr)+v_e_ipdft_max.i*sin(M_PI*e_delta_corr));
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v1.i = e_a*(-v_e_ipdft_max.r*sin(M_PI*e_delta_corr)+v_e_ipdft_max.i*cos(M_PI*e_delta_corr));
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}
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}
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phasor = v1;
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delta = e_delta_corr;
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}
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}
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// end e_ipDFT
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fold = f;
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Xk[km].f = (km + 1 + startBin + delta) * phasorRate;
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if (fold > 0) {
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dfold = df;
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df = (f - fold)*phasorRate;
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d2fold = d2f;
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d2f = (d2f - d2fold)*phasorRate;
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if (abs(df)>3 || abs(d2f>25 || state_rocof)) {
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state_rocof = true;
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rocof = 0.2043*df + 0.2043*dfold + 0.5913*rocof;
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if (abs(rocof) < 0.035) {
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state_rocof = false;
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}
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} else {
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rocof = df;
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}
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}
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if (abs(delta) < 0.00001) {
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estimatedPhasor.amplitude = 2*Xk[km].mag;
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} else {
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estimatedPhasor.amplitude = 2*Xk[km].mag*M_PI*delta*(1-pow(delta, 2)) / sin(M_PI * delta);
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}
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estimatedPhasor.phase = atan2(Xk[km].i, Xk[km].r) - M_PI*delta;
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estimatedPhasor.frequency = Xk[km].f;
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estimatedPhasor.rocof = rocof;
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if (lastPhasor.frequency !=
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0) // Check if we already calculated a phasor before
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estimatedPhasor.valid = Status::VALID;
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return estimatedPhasor;
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}
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};
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// Register hook
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static char n[] = "truncated-ip-dft-pmu";
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static char d[] = "This hook calculates a phasor based on truncated ipDFT";
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static HookPlugin<TruncatedIpDftPmuHook, n, d,
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(int)Hook::Flags::NODE_READ | (int)Hook::Flags::NODE_WRITE |
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(int)Hook::Flags::PATH>
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p;
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} // namespace node
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} // namespace villas
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