Forms of Distributed Energy Resources (DER) have been used in Utility operations for decades, but as Distributed Generation (DG) has become increasingly important to the electric grid the definition of what DER is has been harder to express. In reviewing the cadre of definitions from NREL, PNNL, CPUC, EPRI, NERC, SEPA, etc. a few common elements of definition stand out. DER is energy generation and storage technologies (typically located at the end user customer premises) and efficiency and demand response programs, as well as electric vehicles. SEPA defines DER as physical and virtual assets that are deployed across the distribution grid, typically close to load, and usually behind the meter, which can be used individually or in aggregate to provide value to the grid, individual customers or both.
Whatever particular definition you want to use, it is clear that as DER proliferates, utilities need some way to monitor and control them in order to operate the grid in a safe and reliable fashion. This requirement leads to the need to implement a DERMS solution. DERMS is a software-based management system for interacting with DER in order to forecast, monitor, control and coordinate their operation on the grid. While several vendors are adding DERMS to their ADMS systems, here we consider DERMS a separate subsystem in the overall solution. As DERMS is a fairly nascent technology there will likely be many changes in the coming years and utilities should be able to update the systems with new DERMS in a modular way.
DERMS remotely changes settings on inverters and local energy management systems. In addition, it provides operational status information of DERs to other systems, while also providing DG forecasts to grid control as a whole. In addition to individual system interactions, DERMS must also be capable of interfacing with aggregators or energy providers who may operate large numbers of individual DERs as a generation or energy aggregate. Working with DG and Storage systems in aggregate simplifies the coordination with the grid as a whole.
As this is a newer technology, care should be taken when considering what system to use. Security will play a vital role in DER operation. Security provisioning in these type of systems has no standardized mechanism. Interface mechanisms between the distributed DERs and control systems is also only weakly defined. Some questions to consider. Does the DER interface over local Wi-Fi and then get backhauled through the internet, or is there some Field Area Network (FAN) technology which must be used to provide the network interface? If this is through a local Wi-Fi connection then the interface will likely be a rest-based inbound connection. This raises issues with frequency of communication and latency of operation. If the Utility interacts through an Aggregator, what is the interface between the two? Is this interface standard or proprietary? What is the regulation necessary to ensure Aggregators act on requests. Many questions remain open as to how DER at large scale will interface with the Utility.
As photovoltaic (PV) energy production and Electric Vehicles (EV) proliferate, it is clear that the Utility must use DERMS to better control a modernized grid. Many decisions must be made both with respect to technology and policy. DER and DERMS will be critical components of the next generation electric grid.