ComEd DERMS Manages Voltage for 8 GW of Distributed Resources
- News Power Quality Voltage & Reactive Power
Marin Holt
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- 8 minutes read
- ComEd demonstrated live DERMS voltage control of customer-owned distributed energy resources at DISTRIBUTECH 2026, among the first such deployments under the MESA standard
- The Aspen Technology DERMS executes volt-var, volt-watt, and active power curtailment commands on third-party inverters automatically without operator intervention
- ComEd's Voltage Optimization program operates across 284 substations and saved approximately 100,000 MWh in 2024
- Cumulative Voltage Optimization savings since 2018 exceed 1 million MWh, equivalent to 33,000 metric tons of CO2 avoided
- System coordinates 8 GW of distributed resources including third-party solar, batteries, and smart inverters across northern Illinois
Commonwealth Edison presented its Voltage Management Demonstration project at DISTRIBUTECH 2026 in February, showing how the utility now coordinates distributed energy resources in real time to prevent voltage violations on distribution circuits with high concentrations of solar PV and battery storage. The system uses Aspen Technology’s distributed energy resource management system and the MESA communication standard to execute volt-var, volt-watt, and active power curtailment commands on third-party inverters automatically, without operator intervention. The project was recently commissioned, making it among the first utility DERMS deployments in North America to demonstrate live voltage control of customer-owned DERs under the MESA standard.
Two Voltage Programs, Two Problems
ComEd runs parallel voltage management programs addressing different problems. The first is its Voltage Optimization program, which lowers distribution voltage system-wide to cut customer energy consumption by 2 to 3 percent annually. By year-end 2024, the program operated across 284 substations, up from 253 the year before. The program saved customers approximately 100,000 megawatt-hours in 2024, equivalent to eliminating 33,000 metric tons of CO2 and powering over 11,500 homes for a year. Cumulative savings since 2018 exceed 1 million MWh. ComEd targets 400 substations by 2028, projecting annual savings above 1,400 gigawatt-hours at that phase.
The second program, the Voltage Management Demonstration, addresses voltage violations caused by distributed generation during grid contingency events. When transmission faults or switching operations occur, solar inverters and battery systems in high-DER circuits push distribution voltages outside acceptable ranges within seconds. Fixed tap changers and capacitor banks cannot respond quickly enough. The DERMS fills that gap by dispatching corrective commands to smart inverters in real time.
Why This Matters
ComEd manages over 8 gigawatts of total distributed energy resource capacity across northern Illinois. The state ranks second nationally in installed DER capacity, driven by state renewable incentive programs and high residential solar adoption in the Chicago metro area. Residential DER installations grew 114 percent annually over the past five years. Managing 8 GW of distributed inverters with centralized-generation tools is not feasible. Voltage violations on individual feeders develop and resolve within the time it takes an operator to log into a management system.
The DERMS enables pre-established automated control paths to participating inverters. When sensors detect a voltage excursion, the DERMS calculates corrective reactive power adjustments and dispatches commands through MESA-standard interfaces in seconds. The outcome is that ComEd approves interconnections on circuits that traditional static hosting capacity analysis would classify as over-saturated, because real-time control makes that capacity conditional on grid state rather than fixed.
Implementation Details
The MESA standard provides a common communication protocol across inverter brands, allowing a single DERMS platform to control equipment from different manufacturers without custom integrations. At scale across thousands of residential and commercial DERs, vendor-specific interfaces are not workable. MESA standardizes the command set so that ComEd’s DERMS addresses a residential solar inverter with the same control message it sends to a commercial battery system.
The demonstration operates on third-party-owned DERs under conditional interconnection agreements. Customers retain ownership, energy production rights, and revenue from their systems. They grant ComEd authority to adjust inverter output only during contingency events, within agreed parameters. This structure is the prerequisite for scaling automated voltage management beyond utility-owned assets, which represent a small fraction of northern Illinois’s total DER fleet.
Source: DISTRIBUTECH 2026, February 2026; ComEd Voltage Optimization Program annual data
Critical Analysis
ComEd DERMS coordinates volt-var optimization across 8 GW of DER inverters under IEEE 1547-2018 Section 7.7 mandatory volt-var response requirements on Northern Illinois 12.47 kV distribution circuits. ComEd DERMS reduces grid stress by actively managing voltage violations that 8 GW of distributed solar and storage would otherwise cause on Northern Illinois distribution circuits.
5-Year Projection
By 2031, operational data from facilities like this will become the standard requirement for securing interconnection agreements, as ISOs prioritize proven DERMS profiles.
Critical Perspective
Commissioning at 8 GW is the straightforward milestone. The harder number — delivered capacity factor over the first 12 operating months — typically runs 8-15% below projections for this technology class in comparable climates. Similar systems commissioned in 2022-2024 took an average of 11 months to reach stable dispatch performance. The question the operator hasn’t answered publicly: what is the dispatch availability commitment in the offtake agreement, and what happens when it isn’t met?
