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City Council hears presentation on new electric distribution model to analyze future loads and resilience
Summary
Consultants from Colas LLC outlined a geospatial electric grid model the city will use to simulate loading, test scenarios including large solar interconnections and electrification, and plan short- and long-term upgrades. Staff said the city will host the model and train personnel; subscription and build costs were discussed.
City leaders on July 15 heard a presentation from Colas LLC on a new electric distribution model designed to simulate the city’s distribution network and support planning for future loads and reliability. The consultants said the model will be used to test current conditions and project changes two, six and 20 years into the future.
The consultants told the City Council why the model is needed and how staff will use it. “The purpose … is used to simulate the electric distribution system,” said John McMurray of Colas LLC. He said the tool ties a geospatial data set — wires, transformers, switches and other equipment — into a load-flow simulation that can reveal overloaded equipment, voltage and phasing issues and other conditions.
City and consultant officials said the model will allow staff to run scenarios before investing in equipment. “If there’s an overloaded transformer,” consultant Corey Sandvin said, “what you do is you go, you replace it with the next size bigger. But maybe in 3 years, you gotta replace that transformer again. The purpose of the model is to evaluate your forecast to see if maybe the next size isn’t really what you wanted to install.”
The consultants described several near-term analysis tasks. They said they will study specific connection requests, such as an 800-kilowatt rooftop system proposed for a local Walmart, and examine harmonics, inverter interactions and whether filters or other mitigations will be required. McMurray said the utility’s peak load is about 22 megawatts and the Walmart array would be “less than a half a megawatt” at typical output, so the immediate local effect is small but not negligible.
Council members asked about ownership and maintenance. Mike Luther, the city’s utility director, confirmed the city will host its own instance of the subscription software. McMurray said the software is subscription-based and that the city would hold its own version; he estimated the subscription at $30,000 a year and the consultant effort to build the initial model at roughly $7,000–$9,000.
Councilors also asked about resiliency and collaboration with Vandenberg Space Force Base. McMurray said Colas has met with Vandenberg’s electrical staff and with a consultant working for the base and that the model can test scenarios such as extending the grid to take additional large loads (including a potential prison load) or siting a new substation.
Staff said two city machines now have the software installed and training for city employees has begun; consultants said the city should reload GIS updates roughly once or twice per year and that staff can maintain the model after training. McMurray described the model as a tool for operational planning, reliability analysis and planning for gradually increasing electrification driven by state policy.
Councilors asked follow-up questions about how the model accounts for equipment age and how it can reduce line losses by balancing phases. Consultants said the model’s primary inputs are equipment configuration and loading; if asset-age data are provided they can be included in reliability or life-cycle analyses. The consultants also said the model can show optimal switching actions to reduce outage durations.
The council did not take a formal vote on the presentation. Staff said they would distribute the list of planned new loads to council members, and the consultants said they would email the full 14-page project list to city staff for distribution.
