Transmission Support and Avoidance of Congestion Charges

Electricity storage improves the performance of the transmissionAn interconnected group of lines and associated equipment for the movement or transfer of electric energy between points of supply and points at which it is transformed for delivery to customers or is delivered to other electric systems. system to the extent that it increases the loadAn end-use device or an end-use customer receiving electric powerThe rate at which energy is generated, converted, transmitted, distributed or delivered. and using electric energy from the electrical system (grid). Note: The term load is sometimes treated as a synonym for demand, which is the measure of power that a load receives or... carrying capacityThe rate at which equipment can either generate, convert or transfer energy1. Energy is the potential of a physical system to perform work. (A common unit of work is foot-pound—the amount of energy needed to lift one pound up a distance of one foot.) Energy exists in several forms such as electromagnetic radiation .... of the transmission system, a benefit accrues if additional load carrying capacity defers the need to add more transmission capacity and/or additional T&D equipment. This provides a benefit to the owner of the transmission system. 

Utilities that do not own transmission facilities pay those who do for transmission “service”. Thus, when non-owners use the transmission system to move energy from one place to another the owners impose an “access” chargeThe process of injecting energy to be stored into the storage system. to cover carrying charges and operations and maintenanceExpenses related to operation and maintenance of equipment or facility. costs. Today, transmission capacity for a transaction can include an access charge, which is scaled with overall power flow in the corridor, not just a linear relationship based on needed power flow. The end userThe person or entity that uses energy, as distinct from, for example, entities that engage in wholesale energy transactions or purchases made by a landlord or other “distributor.” may avoid these charges by installing electricity storage. 

NOTE: avoided congestion charges is an established financial opportunity. It is related to too many kWh for the Transmission system to transmit based on rated capacity. The price is set by ISOs. 

The Transmission Support application is really used to modify the “electrical performance” of the system, per the EPRI/DOE Handbook. DischargeThe process of extracting stored energyThe energy available in the storage system to perform physical work through the conversion of its chemical or mechanical energy, stated in kWh or MWh. from the storage system., the storage duration is probably just a few seconds.