Implementation of the PMU estimator based on the Iterative Enhanced Interpolated DFT Algorithm. More...

#include <stdio.h>
#include <complex.h>
#include <math.h>
#include <stdlib.h>
#include "iniparser.h"
#include "pmu_estimator.h"

Include dependency graph for pmu_estimator.c:

Macros
#define	NUM_CHANLS 1
	Number of channels to process (can be defined at compile time)

#define	DEBUG 3
	Debug logging level - includes all messages.

#define	INFO 2
	Info logging level - includes info and error messages.

#define	ERROR 1
	Error logging level - only error messages.

#define	LOGGING_LEVEL ERROR
	Current logging level (can be defined at compile time)

#define	error(...) fprintf(stderr, __VA_ARGS__)
	Error logging macro - outputs to stderr.

#define	info(...)
	Info logging macro - outputs to stdout.

#define	debug(...)
	Debug logging macro - outputs to stdout.

#define	debug_bins(...)

#define	wrap_angle(rad) (((float_p)(rad) - 2 * M_PI_p * rint((float_p)(rad) / (2 * M_PI_p))))
	Wraps an angle to the range [-π, π] radians.

#define	sineasin(x) (pmue_sin(M_PI_p * (x)) / pmue_sin(ctx->hann_params.C4 * M_PI_p * (x)))
	Sine-over-sine ratio used in Hanning window DFT.

#define	whDFT(x) (pmue_cexp(-I * M_PI_p * ctx->hann_params.C3 * (x)) * (ctx->hann_params.C5 * sineasin((x) - 1) + ctx->hann_params.C1 * sineasin((x)) + ctx->hann_params.C6 * sineasin((x) + 1)))
	Hanning window DFT formula.

#define	wf(k, f, in_phsr) ((in_phsr) * whDFT((k) - ((f) / ctx->synch_params.df)) * (ctx->hann_params.inv_norm_factor))
	Weighted frequency bin calculation.

Functions
int	pmu_init (pmu_context ctx, void cfg, bool_p config_from_ini)
	Initialize a PMU estimator instance.

int	pmu_estimate (pmu_context ctx, float_p in_signal_windows, float_p mid_fracsec, pmu_frame *out_frame)
	Estimate synchrophasor, frequency, and ROCOF from input signal.

int	pmu_deinit (pmu_context *ctx)
	Deinitialize and free resources of PMU estimator instance.

int	pmu_dump_frame (pmu_frame frame, FILE stream)
	Print PMU frame data to output stream.

Detailed Description

Implementation of the PMU estimator based on the Iterative Enhanced Interpolated DFT Algorithm.

This file contains the complete implementation of a Phasor Measurement Unit (PMU) estimator that uses advanced signal processing techniques to accurately estimate synchrophasors, frequency, and Rate of Change of Frequency (ROCOF) from power system signals.

Algorithm Overview

The implementation uses the Iterative Enhanced Interpolated DFT (Discrete Fourier Transform) algorithm with the following key features:

Hanning Window: Applied to reduce spectral leakage
Interpolated DFT (ipDFT): Improves frequency resolution beyond FFT bin spacing
Enhanced ipDFT (e-ipDFT): Compensates for interference from nearby frequency components
Iterative Refinement: Multiple iterations improve accuracy under dynamic conditions
ROCOF Estimation: Calculates the rate of frequency change with low-pass filtering

Key Features

Multi-channel signal processing (configurable via NUM_CHANLS)
Configurable via INI file or structure
M-Class and P-Class PMU configurations supported
Optimized FFT for power-of-2 window sizes
Comprehensive logging system (ERROR, INFO, DEBUG levels)
Memory-efficient with dynamic allocation

Author: Chemseddine Allioua, Brahim Mazighi

Copyright: Copyright (c) 2023. All Rights Reserved. Confidential and Proprietary - University of Bologna.

Version: 1.7.0

Macro Definition Documentation

◆ DEBUG

#define DEBUG 3

Debug logging level - includes all messages.

◆ debug

#define debug ( ... )

Debug logging macro - outputs to stdout.

◆ debug_bins

#define debug_bins ( ... )

◆ ERROR

#define ERROR 1

Error logging level - only error messages.

◆ error

#define error ( ... ) fprintf(stderr, __VA_ARGS__)

Error logging macro - outputs to stderr.

◆ INFO

#define INFO 2

Info logging level - includes info and error messages.

◆ info

#define info ( ... )

Info logging macro - outputs to stdout.

◆ LOGGING_LEVEL

#define LOGGING_LEVEL ERROR

Current logging level (can be defined at compile time)

◆ NUM_CHANLS

#define NUM_CHANLS 1

Number of channels to process (can be defined at compile time)

◆ sineasin

#define sineasin ( x ) (pmue_sin(M_PI_p * (x)) / pmue_sin(ctx->hann_params.C4 * M_PI_p * (x)))

Sine-over-sine ratio used in Hanning window DFT.

◆ wf

#define wf	(	k,
		f,
		in_phsr ) ((in_phsr) * whDFT((k) - ((f) / ctx->synch_params.df)) * (ctx->hann_params.inv_norm_factor))

Weighted frequency bin calculation.

◆ whDFT

#define whDFT ( x ) (pmue_cexp(-I * M_PI_p * ctx->hann_params.C3 * (x)) * (ctx->hann_params.C5 * sineasin((x) - 1) + ctx->hann_params.C1 * sineasin((x)) + ctx->hann_params.C6 * sineasin((x) + 1)))

Hanning window DFT formula.

◆ wrap_angle

#define wrap_angle ( rad ) (((float_p)(rad) - 2 * M_PI_p * rint((float_p)(rad) / (2 * M_PI_p))))

Wraps an angle to the range [-π, π] radians.

Function Documentation

◆ pmu_deinit()

int pmu_deinit ( pmu_context * ctx )

Deinitialize and free resources of PMU estimator instance.

Releases all dynamically allocated memory associated with the PMU context and resets the initialization flag. After calling this function, the context can be reinitialized with pmu_init() if needed.

Parameters

[in,out] ctx Pointer to the PMU context to deinitialize

Returns: 0 on success, -1 on error

Note: Always call this function when finished with a PMU context to prevent memory leaks.

See also: pmu_init()

◆ pmu_dump_frame()

int pmu_dump_frame	(	pmu_frame *	frame,
		FILE *	stream )

Print PMU frame data to output stream.

Outputs the contents of a pmu_frame structure in a human-readable format to the specified output stream (e.g., stdout, stderr, or a file).

Parameters

[in]	frame	Pointer to the PMU frame to dump
[in]	stream	Output stream (e.g., stdout, stderr, or FILE pointer from fopen)

Returns: 0 on success, -1 on error

See also: pmu_frame

◆ pmu_estimate()

int pmu_estimate	(	pmu_context *	ctx,
		float_p *	in_signal_windows,
		float_p	mid_fracsec,
		pmu_frame *	out_frame )

Estimate synchrophasor, frequency, and ROCOF from input signal.

This is the main estimation function that processes a window of input samples and produces synchrophasor and ROCOF estimates using the Iterative Enhanced Interpolated DFT algorithm.

Parameters

[in]	ctx	Pointer to initialized PMU context
[in]	in_signal_windows	Pointer to input signal samples. For multi-channel: array of pointers to signal windows for each channel. Array size must match NUM_CHANLS configuration.
[in]	mid_fracsec	Fractional second timestamp (relative to PPS) of the midpoint of the observation window. Used for phase correction.
[out]	out_frame	Pointer to output PMU frame structure where results are stored

Returns: 0 on success, -1 on error

Warning: The size of in_signal_windows must match the NUM_CHANLS setting used during compilation. Mismatch will cause segmentation fault.

Note: The context must be initialized with pmu_init() before calling this function.

See also: pmu_init(); pmu_frame

◆ pmu_init()

int pmu_init	(	pmu_context *	ctx,
		void *	cfg,
		bool_p	config_from_ini )

Initialize a PMU estimator instance.

Initializes a PMU estimator context with the specified configuration. The configuration can be loaded from an INI file or passed as a structure.

Parameters

[in,out]	ctx	Pointer to the PMU context structure to initialize
[in]	cfg	Configuration: either a filename (char*) if config_from_ini=1, or a pointer to an estimator_config structure if config_from_ini=0
[in]	config_from_ini	Configuration source flag: CONFIG_FROM_INI (1): Load from INI file CONFIG_FROM_STRUCT (0): Use structure

Returns: 0 on success, -1 on error

Note: The context should not be already initialized. Call pmu_deinit() first if reinitializing an existing context.

See also: pmu_deinit(); estimator_config

Macros

Functions

Detailed Description

Algorithm Overview

Key Features

Macro Definition Documentation

◆ DEBUG

◆ debug

◆ debug_bins

◆ ERROR

◆ error

◆ INFO

◆ info

◆ LOGGING_LEVEL

◆ NUM_CHANLS

◆ sineasin

◆ wf

◆ whDFT

◆ wrap_angle

Function Documentation

◆ pmu_deinit()

◆ pmu_dump_frame()

◆ pmu_estimate()

◆ pmu_init()