Integrated Economic and Reliability Planning: A use case for system operators, utilities, and reliability organizations
An integrated economic and reliability planning study answers a question that siloed processes cannot: what is the least-cost mix of generation and transmission that still holds up under AC power flow and contingency analysis, hour after hour across the year? This document describes how SAInt makes that question answerable, and what the answer means for planning teams.
The Challenge: When Economics and Reliability Are Planned Apart
The industry needs new generation and new transmission at the same time, and the two have to be planned together. In most organizations they are not. Capacity expansion runs on a zonal view of the system and production cost modeling on a nodal DC view. Transmission reliability, meaning AC power flow and contingency analysis, runs higher detail nodal models that include all voltage related equipment, in another set of tools. Often, internal ad hoc scripts move data between them.
That hand-off is where planning breaks. Economic results and physical results drift apart, data streams are error-prone, iteration is slow, and studies are hard to reproduce or audit. A least-cost expansion plan can look sound on the economic model and prove infeasible once it meets AC power flow and contingencies. The gap is often discovered years later, when the cost of changing course is highest.
Traditional power flow studies only examine a handful of snapshots, typically peak demand conditions in each season. Reliability risks that surface in specific load pockets, or in unusual but credible operating conditions, fall between a zonal economic plan that cannot see them and a nodal reliability study that checks only a few cases. Planning teams are left to reconcile two models by hand, with little time to explore alternatives.
Economic plans and reliability plans are built in different tools, on different models, by different teams. When they disagree, the system pays for it years later. SAInt plans them as one.
How SAInt Addresses This: One Model, From Economics to Reliability
SAInt, encoord's integrated planning software, was developed specifically for economic and reliability planning problems that require iteration between capacity expansion modeling, security-constrained production cost modeling, AC power flow simulations, and contingency analysis. Integrated generation and transmission planning is a primary application.
The foundation of each study is an Integrated Planning Model (IPM), a single representation of the system that carries all of the inputs needed to run capacity expansion modeling, security-constrained production cost modeling, AC power flow simulations, and contingency analysis. The IPM is built on the most detailed view any step requires, the transmission planning case, so that economic and reliability studies draw from one source of truth rather than separate models that must be reconciled. encoord calls this principle highest detail first. Zonal capacity expansions are executed on reduced networks derived directly from these planning cases . SAInt's Integrated Planner then maps each economic dispatch into an aligned AC power flow snapshot, preserving dispatch levels, commitment status, topology, and operating constraints across every simulation timestep.
From that single model, SAInt runs the full planning cycle: capacity expansion to choose a least-cost resource and transmission build, full-year hourly production cost modeling to dispatch it, and reliability analysis to test it with AC power flow and contingency analysis. Reliability results feed back into the economics, so violations become enforceable constraints or targeted upgrades rather than surprises discovered late. Because every step runs on the same model, results are traceable and auditable, not a “black box,” and defensible for regulatory filings and stakeholder review.
Running on one model removes the arduous and error-prone manual data hand-offs between steps, making it practical to plan against the full 8,760 hours of the year and large contingency sets instead of a few snapshots. The same workflow can be automated and repeated across scenarios, so teams explore alternatives in the time a single reconciled study used to take. SAInt can run the reliability analysis with its native AC power flow solver or interoperate with industry-standard tools.
Inputs and Outputs
An integrated economic and reliability planning study in SAInt requires: a transmission planning case as the network foundation, generator operational and cost data, time-series for load, wind, and solar power, investment candidates and demand forecasts for capacity expansion, and the applicable contingency set. It produces:
A least-cost generation and transmission expansion plan, evaluated against reliability rather than economics alone.
Full-year hourly production cost results: dispatch patterns, congestion, binding constraints, and locational price impacts.
Reliability results from AC power flow and contingency analysis, with voltage and thermal violations expressed as enforceable constraints or candidate upgrades.
The critical and at-risk operating hours across the full year, identified from the economic simulation rather than assumed in advance.
Traceable expansion decisions, each tied to the assumptions behind it, reproducible and auditable across scenarios.
Beyond a handful of cases
Traditional studies plan against a few seasonal snapshots. Because SAInt runs on a single model with the hand-offs automated, planning teams can test thousands of operating conditions across the year, surfacing stress periods and reliability constraints that a handful of cases would never reveal.
SAInt has been adopted by multiple utilities, system operators, developers, and consulting firms across North America to advance grid planning processes.
Plan generation and transmission as one system
Whether you are integrating resource and transmission planning, exposing reliability constraints hidden in an economic plan, or building a repeatable integrated study process, encoord can stand up the workflow in SAInt.
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