ERCOT White Paper Makes Pitch For Greater Visibility Into Distributed Energy Resources, Growth
March 27,2017
ERCOT released a white paper proposing steps to increase its visibility into distributed energy resources (DERs) to ensure reliable operation of the bulk power grid.
The white paper notes that, "Based on installed capacity and current rates of growth, these resources do not pose an immediate or near-term reliability concern for the transmission grid. The environment for DERs in ERCOT is characterized by a combination of low energy prices and an absence of region-wide regulatory incentives, leading to a penetration growth rate that is much slower than has been witnessed in other regions such as Germany, California and Hawaii."
"Nevertheless, many factors — including customer desire for independence, environmental consciousness, and declining costs of DER acquisition — point to continued growth. Thus far within ERCOT, additional drivers for DER growth have included participation in Emergency Response Service (ERS), demand-charge avoidance in the form of Four Coincident Peak (4CP) response, and Load Zone-level wholesale price response in the Real-Time Energy Market. The ERCOT Independent System Operator (ISO) would like to be prepared for a future scenario in which a larger share of the regional generation mix may come from the distribution system," the white paper states
"ERCOT believes the foundation to the reliable and efficient management of this future distributed grid is visibility, in the form of more detailed collection of static DER data from Distribution Service Providers (DSPs) and Transmission Service Providers (TSPs) to support various ERCOT grid monitoring functions. ERCOT does not propose to model or operate the distribution system; that remains the sole province of the DSPs. Rather, ERCOT proposes a collaborative process involving DSPs and TSPs in which the locations of large DERs or large clusters of small DERs are mapped to their appropriate modeled transmission loads (Common Information Model, or CIM Loads) in the ERCOT Network Operations Model (NOM)," the white paper states
ERCOT acknowledges that these entities do not currently have processes in place to map DERs to CIM Loads, and the white paper therefore proposes the following transition:
1. ERCOT in 2017 will work with TSPs and DSPs to develop a standardized method of providing and collecting appropriate data for mapping current and future registered DER units to their CIM Loads, considering the normal circuit operating configuration of the DER. TSPs will retain their current flexibility in determining how to model the CIM Loads in their networks, and will have the ability to relocate a mapped DER to a different CIM. This will affect approximately 85 existing units, all of which have at least 1 MW in rated capacity and export power to the grid. The vast majority of this capacity falls into the “self-dispatched” category; mapping these units to their CIM Loads will provide the ISO with locational awareness for more than 80% of total DER Connected Capacity.
2. ERCOT will work with stakeholders to develop a process for competitive choice and NOIE DSPs to monitor the accumulation of clusters of unregistered (<1 MW) DER units connected to specific CIM Loads. When the combined Connected Capacity of these smaller units associated with a specific CIM Load exceeds an agreed-upon threshold, the DSP and TSP can work with ERCOT to determine the best process for providing the data necessary to map these DERs to the CIM. This will provide the ISO with locational awareness for CIM Loads that may be subject to reliability issues due to larger than normal weather-related swings or load swings due to large DER accumulation, while avoiding the need to map thousands of individual DERs (mainly rooftop solar arrays) to the transmission grid. ERCOT does not propose the actual thresholds herein, but rather looks forward to working with TSPs and DSPs to identify them.