A system comprising: an oscillation detector configured to: receive digital data samples indicative of amplitude fluctuations in electricity transmitted through an electrical power grid; process the digital data samples for detecting an oscillatory condition in at least one of five predefined frequency bands; and upon detecting the oscillatory condition, determine at least one of a magnitude characteristic, a phase characteristic, or a damping characteristic of at least one oscillation frequency that contributes to the oscillatory condition; wherein the five predefined frequency bands include a first frequency band spanning from about 0.01 Hz to about 0.1 Hz, a second frequency band spanning from about 0.1 Hz to about 1 Hz, a third frequency band spanning from about 1.0 Hz to about 10.0 Hz, a fourth frequency band spanning from about 10 Hz to about 55 Hz, and a fifth frequency band comprising a DC component; wherein an oscillation frequency within the second frequency band is indicative of an inter-area oscillation; wherein an oscillation frequency within the third frequency band is indicative of a forced oscillation originated by an operational interaction between two or more components coupled to the electrical power grid; wherein an oscillation frequency is within the fourth frequency band is indicative of at least one of a sub-synchronous resonance condition or a sub-synchronous torsional interaction between two components coupled to the electrical power grid Wherein an oscillation frequency within the fifth frequency band is indicative of geomagnetically induced currents present in at least one component that is a part of the electrical power grid; Characterised in that The oscillation detector comprises a signal detector which is configured to perform an envelope extraction procedure upon the digital data samples for detecting the oscillatory condition in the fourth frequency band of the five predefined frequency bands; Wherein a first high-pass infinite impulse response filter is configured to operate upon the digital data samples to output a first filtered digital data stream, yH; a first low-pass finite impulse response filter is configured to operate upon yH, to output a second filtered digital data stream, yL; an orthogonal filter pair (315, 325) is configured to operate upon a real component and a quadrature component of yL, to output digital data streams, yc and ys; decimation blocks are configured to decimate yc and ys to a lower rate to digital data streams xc and xs; an envelope extraction is configured to be carried out upon each of the digital data streams xc and xs; a second high-pass infinite impulse response filter and a second low-pass infinite impulse response filter are configured to filter the output of the envelope extraction. an oscillation detector configured to: receive digital data samples indicative of amplitude fluctuations in electricity transmitted through an electrical power grid; process the digital data samples for detecting an oscillatory condition in at least one of five predefined frequency bands; and upon detecting the oscillatory condition, determine at least one of a magnitude characteristic, a phase characteristic, or a damping characteristic of at least one oscillation frequency that contributes to the oscillatory condition; wherein the five predefined frequency bands include a first frequency band spanning from about 0.01 Hz to about 0.1 Hz, a second frequency band spanning from about 0.1 Hz to about 1 Hz, a third frequency band spanning from about 1.0 Hz to about 10.0 Hz, a fourth frequency band spanning from about 10 Hz to about 55 Hz, and a fifth frequency band comprising a DC component; wherein an oscillation frequency within the second frequency band is indicative of an inter-area oscillation; wherein an oscillation frequency within the third frequency band is indicative of a forced oscillation originated by an operational interaction between two or more components coupled to the electrical power grid; wherein an oscillation frequency is within the fourth frequency band is indicative of at least one of a sub-synchronous resonance condition or a sub-synchronous torsional interaction between two components coupled to the electrical power grid Wherein an oscillation frequency within the fifth frequency band is indicative of geomagnetically induced currents present in at least one component that is a part of the electrical power grid; Characterised in that The oscillation detector comprises a signal detector which is configured to perform an envelope extraction procedure upon the digital data samples for detecting the oscillatory condition in the fourth frequency band of the five predefined frequency bands; Wherein a first high-pass infinite impulse response filter is configured to operate upon the digital data samples to output a first filtered digital data stream, yH; a first low-pass finite impulse response filter is configured to operate upon yH, to output a second filtered digital data stream, yL; an orthogonal filter pair (315, 325) is configured to operate upon a real component and a quadrature component of yL, to output digital data streams, yc and ys; decimation blocks are configured to decimate yc and ys to a lower rate to digital data streams xc and xs; an envelope extraction is configured to be carried out upon each of the digital data streams xc and xs; a second high-pass infinite impulse response filter and a second low-pass infinite impulse response filter are configured to filter the output of the envelope extraction.