One of the greatest challenges utilities face is how to introduce smart grid technology toadapt to a decarbonized, decentralized, and digitized environment. MV/LV substationsare at the core of any electrical power distribution system. They hold the switches,capacitors, transformers, and other assets utilities need to keep grid power flowing,balanced, and routed appropriately. This makes them a prime target for smart gridtechnology to both meet consumers’ ever-growing needs and expectations while alsomanaging the increasing infusion of distributed energy resources (DER) into the grid..
In the second blog of this two-part series (part 1 if you missed it), we’ll continue to examine the issues utilities face and how adding smart technology capabilities to MV/LV substations can help utilities overcome them.
Voltage fluctuations are a major pain point for utilities. They’re costly, inconvenient, affect power quality, safety, and reliability, and can damage customers’ facilities and equipment. The task of managing fluctuations has become more difficult as an influx of DERs have been integrated into the grid. Weather-dependent sources of energy like solar and wind power provide an unsteady, sometimes unstable, supply of power, which forces utilities to more actively monitor and adjust power levels.
There’s an array of technology to combat fluctuations. Smart transformers meet dynamic voltage regulation needs and are an appealing option for utilities that are planning for how they’ll meet their future distribution network challenges. These smart transformers include actuators that can help manage voltage and active and reactive power. They automatically regulate the Medium Voltage to increase or decrease the Low Voltage to keep it within the contractually allowed limits. Another option is feeder switches with intelligent local controls that can constantly monitor the system to identify and react quickly to fluctuations and faults.
Improve LV feeder load balancing
Problems can arise in feeder load balancing when LV ends of distribution networks are unbalanced between transformers, between LV feeders within a transformer, or between the three phases of a particular transformer. Finding this feeder load balance is becoming more difficult as utilities cope with the growing addition of DER, which range from supply-side to demand-side resources, and can magnify the imbalance because of an unsteady power influx.
Better balancing LV feeder loads helps achieve optimal performance and reduces energy loss, which, in turn, cuts costs. Smart technology can improve the feeder load balance by equipping LV readers with energy meters that connect to the remote terminal unit (RMU) in the substation and can calculate imbalances in real-time, as well as rebalancing loads using repartition units.
Avoid unwanted islanding
Intentional islanding — when a distributed generator continues to supply power to a portion of the grid while the main public electrical power grid is no longer present — is a useful tool for utilities, for example, in an emergency when the grid shows signs of impending failure. However, unwanted islanding is a safety hazard and can lead to damage to the distributed generator unit, network components, and customers’ equipment. It most commonly occurs when protection devices located at the DER site don’t properly detect the occurrence and therefore don’t trip or when the incorrect operation of a switch or breaker creates islanding conditions.
Unwanted islanding is becoming a more common occurrence because of the injection of DER, along with the rise of microgrids connected to the distribution network, which both can disrupt system stability. Anti-islanding protection based on communications with the MV/LV substation creates a more flexible, localized option. For example, smart fault passage indicators may be able to warn connected, distributed generation sources of feeder issues and by doing so help avoid islanding part of the grid. Smart technology can be used to force a disconnection by asking the feeder components to communicate with all attached DER.