This invention deals with an advanced Real-time Grid
Monitoring System (RTGMS) suitable for both single-phase and three-phase
electric power systems. This invention provides an essential
signal processing block to be used as a part of complex systems either focused on supervising and diagnosing power systems or devoted to
control power processors interacting with the grid. This invention is based on a new
algorithm very suitable for real-time characterization of the grid variables under distorted and unbalanced grid conditions. The main characteristic of this invention is the usage of a frequency-locked loop, based on detecting the grid frequency, for
synchronizing to the grid variables. It results in a very robust
system response in relation to existing technique based on the phase-angle detection since grid frequency is much more stable variable than the
grid voltage / current phase-angle, mainly during grid faults. Moreover, the
algorithm supporting this invention is very efficient and can be implemented in regular industrial microprocessors. These features make the RTGMS object of this invention ideal to be applied in the control of
distributed generation systems (DGS), flexible AC transmission systems (FACTS),
power quality conditioners (PQC) and uninterruptible power supplies (UPS). In all these systems, the fast and precise real time detection of the
voltage and / or current sequence components under
grid fault conditions is a crucial matter.