3.6 Distribution Resource Planning With DER Systems
3.6.1 Distribution Resource Planning Process in California
In compliance with California’s recent law AB 327, section 769 , California IOU utilities are required to file Distribution Resources Plans (DRP) with the CPUC with annual updates. These DRPs are expected to define (electrical) locational benefits and optimal locations for DER systems, to identify possible augmented or new tariffs and programs to support efficient DER deployment, and to remove specific barriers that may be limiting the deployment of DER systems. The DRPs would be based on sophisticated power-flow-based analysis software which would also include the modeling of different types of DER capabilities. The DRPs would provide roadmaps for distribution system planning requirements for 3-5 years ahead.
The primary purpose of these DRPs is to require utilities to modify their normal distribution planning process to take into account the benefits that DER systems could provide, particularly if different types of DER systems with compensating capabilities can be placed optimally to help defer construction costs, to improve efficiency, and to ensure safety, while still continuing to provide reliable power. Specifically:
- DRPs would identify optimal locations for the deployment of DERs. In the DRP context, DERs could include distributed renewable generation, energy efficiency, energy storage, electric vehicles, and demand response.
- DRPs would evaluate locational benefits and costs of DERs based on reductions or increases in local generation capacity needs, avoided or increased investments in distribution infrastructure, safety benefits, reliability benefits, and any other savings DERs provide to the grid or costs to ratepayers.
- The DRP process would propose or identify standard tariffs, contracts, or other mechanisms for deployment of cost-effective DERs that could satisfy distribution planning objectives. It could also identify how to coordinate existing commission-approved programs, incentives, and tariffs to maximize the locational benefits and minimize the incremental costs of DERs
- The DRP would identify additional utility spending necessary to integrate cost-effective DERs into distribution planning and would determine what barriers might exist to the deployment of DERs, such as safety standards and reliability requirements.
For instance, if energy storage systems can be coupled with feeders that experience strong fluctuations in power due either to the native load characteristics or renewable generation, then the energy storage system can be used to counter these fluctuations. Locating an energy storage system in the feeder’s substation could allow the utility to defer upgrades to the feeder or to avoid adding new voltage management devices.
Another example would be if utilities were able to request that certain DER systems limit their power output at certain times to avoid back feed, to correct serious over-voltage situations, or to stay within the Conservation Voltage Reduction (CVR) limits. Utilities could either issue commands or could activate the advanced volt-var control function of selected DER systems. This approach would both permit more DER systems to be interconnected on such a “sensitive” feeder as well as avoiding additional utility costs for voltage regulation equipment.
For the purposes of distribution resource planning, “DER” is defined as including not only the generators, energy storage, and controllable loads, but also energy efficiency and demand response. In other words, the concept of “distribution resources” which are available for use in planning is expanded to incorporate any measures that might affect distribution operations.