Across markets globally the distribution grid is rapidly moving away from being a passive network due to the proliferation of small embedded generation (PV, wind, heat pumps etc.) as well as the imminent introduction of Electric Vehicles (EV). In order to control these networks and maintain both security and quality of supply it is necessary to start deploying control devices in these traditionally passive networks. These can include on-line tap changers, in-line regulators, switched capacitors and in the future energy storage. For instance distributed switched capacitors can be used to minimise the amount of VARs required from centralised generation, in turn helping utilities achieve greater system efficiency and capacity.
Recent technology enhancements offered through advanced Volt-VAR controls determine whether devices are turned off or on by taking real-time measurements and analysing the associated VAR flows. This allows utilities to optimise the system across all feeders served by a substation, eliminating the common scenario where one feeder has a leading power factor, while another has a lagging power factor but the substation bus has met the target power factor.
Centralised intelligence allows utilities to consistently manage the grid based on live conditions, enabling them to balance the system properly on an overall substation level basis to maximise efficiency. Centralised intelligence works optimally with distributed, intelligent controls, offering the autonomy and flexibility to revert back to local control in the event communications are lost. Innovations in Volt-VAR management technology are enabling the industry to move closer to the holy grail of maintaining a unity power factor across all operating conditions.
A layered intelligence approach using both centralised and distributed intelligence will allow utilities to gradually roll out smart grid components whilst realising immediate benefits. A Volt-VAR system can be introduced first in geographies with a higher penetration of EVs or distributed renewable generation, and added later to areas where these technologies are not yet in wide use. Volt-VAR can also be layered in with self-healing and distributed energy management to provide additional layers of intelligence that will improve voltage and VAR support under different operating conditions and system topology changes.
Layered intelligence can also be implemented by allowing local control logic to work in conjunction with the centralised control logic within the Volt-VAR system. Such an approach offers a robust system design, eliminating vulnerability to a single point of failure, which might otherwise cause the system to lose all functionality. So, in the event that communications are compromised, the system would continue to function through the distributed intelligence at a slightly less optimal level. Systems that lack this layered intelligence approach are at risk to communication or system disruptions.
Employing a layered intelligence approach can provide precise, effective functionality across the entire grid. These platforms, which work with enterprise-level utility systems, ensure that utilities can take the important step toward fulfilling the potential of a true smart grid and move closer to achieving unity power factor.
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