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Hosting Capacity Map

The Ameren Illinois Company (AIC) hosting capacity maps display a high-level visualization of the available hosting capacity for interconnecting distributed energy resources (DER) to an AIC electrical system. Hosting capacity is defined as the approximate amount of generation that can be accommodated at a given point in time on the system without impacting reliability, requiring specialized inverter settings, or without requiring system modifications. The capacity values are meant to provide the user with a general idea of capacity at a location, however it is not guaranteed and/or may change at any time. All applications for interconnection will still require a full engineering review subject to Illinois Administrative Code guidelines and may require additional system modifications that could increase interconnection costs.

The hosting capacity map is offered free of charge and correspondingly is not as accurate, detailed, or specific as the results obtained through the Interconnection Application process. The map is developed from available Ameren Illinois data and updated in accordance with policy, and therefore may not reflect current conditions in a given area. The map is being provided for informational purposes only and is not intended to be a substitute for the established interconnection process.

The distribution hosting capacity map provides results for system voltages of 15 kV and lower. Recommended interconnection sizes to evaluate with this map are 5 MVA and below due to the nature of systems operating at this voltage.

The subtransmission hosting capacity map provides results for system voltages at 34.5 kV and 69 kV represented as areas. Recommended interconnection sizes to evaluate with this map are 10 MVA or greater and no less than 5 MVA due to the cost of interconnection equipment required at these voltages. If multiple values are located within an area, the resulting hosting capacity is averaged and reported on the map.

AIC distribution hosting capacity analysis takes into consideration several operating factors and conditions including voltage, loadings, and voltage stability. An incremental nodal hosting capacity methodology is used to derive hosting capacity values at substations and along feeders using power flow simulation software. For each node in the power flow model, PV generation is added and simulations are run while incrementally increasing generation output. System limitations are then identified by analyzing power flow results at minimum and maximum loading, and the lowest value from either scenario is then deemed the available hosting capacity for that node. The subtransmission analysis builds on this by providing both normal and n-1 contingency system operating condition results. Specific needs such as metering, coordination and adequacy of system protection devices, or other additional site-specific infrastructure are not addressed with the hosting capacity analysis and would be identified during the review process of the interconnection study agreement.

The subtransmission analysis builds on this process by providing both normal and n-1 contingency system operating condition results. "Normal Conditions" are the present, everyday state of the electric system with equipment in-service and operating as expected. Whereas, "Contingency Conditions" represent an abnormally switched state of the electric system in response to either an unplanned or planned outage of a system component (e.g. transformer, line segment, capacitor back, etc.). N-1 contingency conditions refer to a single event and the system's response to that event. Subtransmission interconnection studies consider normal operating conditions and hundreds of abnormal system conditions. Our intention of providing both values is to provide insight into the feasibility of interconnecting generation at a given location. We use the same power flow modeling software and criteria during studies as are used to calculate the hosting capacity values.

Projects in the study and interconnection queues that have not yet executed an interconnection agreement may have an impact on hosting capacity. AIC lacks certainty on whether these projects will proceed, therefore, the impacts of these potential projects are not reflected in the hosting capacity values shown on the maps.

This narrative will summarize Ameren Illinois' hosting capacity analysis strategy as well as explain how it will support and advance the interconnection of customer-sited distributed energy resources (DER) as required by Section 16-105.17(f)(2)(E) of the Public Utilities Act:

The utility shall make available on its website the hosting capacity analysis results that shall include mapping and GIS capability, as well as any other requirements requested by the Commission or determined through Commission rules. The plan shall identify where the hosting capacity analysis results shall be made publicly available. This shall also include an assessment of the impact of utility investments over the next 5 years on hosting capacity and a narrative discussion of how the hosting capacity analysis advances customer-sited distributed energy resources, including electric vehicles, energy storage systems, and photovoltaic resources, and how the identification of interconnection points on the distribution system will support the continued development of distributed energy resources.

Ameren Illinois understands the value in hosting capacity as an enabling activity supporting the efficient interconnection of DERs onto the electrical grid. We foresee hosting capacity advancing customer sited DERs as it will provide more transparency around available capacity on the grid, and guide installations to locations that have the least constraints. In turn, this will reduce the volume of applications that are not viable, which provides opportunities for more efficiencies to be gained from an Ameren Illinois resource standpoint as well as from the developers' standpoint as they will be less likely to devote time and effort to a non-viable site. The hosting capacity studies and related results will provide value with the interconnection process and evolve at the rate of customer interest while prioritizing the safety and reliability of the distribution system and the protection of sensitive system information.

Hosting capacity analysis estimates the amount of DERs that can be interconnected to the distribution system without requiring major system modifications or upgrades. The results can be published in a public facing GIS (Geographic Information System) solution which can be used by third party developers early in the interconnection and application process. Ameren Illinois hosting capacity analysis takes into consideration several operating conditions including voltage, loadings, and voltage stability. An iterative nodal hosting capacity methodology is used to derive hosting capacity values at the feeder level. At each node of a circuit, a DER is modeled and its output is incrementally changed over multiple power flow simulation scenarios. System limitations are identified by analyzing power flow results at minimum and maximum loading, and the lowest value determined from the multiple power flow simulation scenarios is deemed the available hosting capacity for that node. Additionally, the subtransmission analysis provides a second set of results based on n-1 contingency conditions to highlight system constraints that may impact the maximum amount of available capacity. These values will be input into GIS that will be published as a hosting capacity heat map for third party users to view. When the user displays the map, they will be able to search for a specific address or use other zoom functionality like the zoom in (+) and zoom out (-) buttons or by scrolling with a mouse. As they zoom in hosting capacity data will present itself in an aggregated grid format. The hosting capacity value for circuits running through the grid, the operating voltage, phase designation, and orientation will be shown once the user clicks on the color-coded grid. Also, a link to the Ameren Illinois Distributed Generation webpage is available so the user can go directly to the page and gather valuable information regarding the application process in addition to initiating the interconnection application.

Data accuracy within GIS has a direct impact on hosting capacity values. With this understanding, Ameren Illinois spent significant time reviewing asset attributes for devices installed on the distribution system to improve data quality within GIS. A thorough data validation effort was also completed prior to posting hosting capacity values where specific screens were completed on a sample of the hosting capacity values that were calculated across the Ameren Illinois service territory. While numerous refinements were made as part of this effort, Ameren Illinois does believe that managing the accuracy of GIS data and validating hosting capacity results with each new release will be an ongoing effort. New assets are placed into service, legacy assets are retired, and data quality improvements happen daily throughout Ameren Illinois' service territory. For this reason, we want to reiterate that the hosting capacity maps should not be viewed as a substitute to the formal interconnection process and related studies. Ameren Illinois is committed to resolving imperfections and issues that are identified within the hosting capacity maps and will strive to continuously improve and enhance the maps as the hosting capacity strategy matures.

Ameren Illinois also realizes the importance of working collectively with third-party stakeholders to incorporate their input into programs and initiatives like the hosting capacity analysis effort. As such, Ameren Illinois spent time socializing the hosting capacity map with expected users to gather valuable feedback as to how the solution can be enhanced. Their input and feedback were received during a demonstration of Ameren Illinois’ hosting capacity maps. Input received was prioritized and implemented into the hosting capacity maps to ensure value added with the end product. Ameren Illinois also spent time collaborating with industry research groups such as Electric Power Research Institute and Interstate Renewable Energy Council to make sure lessons learned from other utilities could be incorporated into our hosting capacity strategy.

Ameren Illinois expects the methodology and strategy behind the hosting capacity implementation to mature over time as opportunities arise that allow us to provide further value. This will have a direct impact on Ameren Illinois' capital investment strategy over the next 5 years as Ameren Illinois will look to make investments that positively impact available hosting capacity on the electrical grid by incorporating the hosting capacity strategy into the distribution planning process. Examples of investments that may benefit hosting capacity include 4 kV to 12 kV conversions, upgrades to distribution protection equipment such as reclosers and breakers, and the implementation of controls and coordination oversight on DER assets through the use of DERMS. The Ameren Illinois hosting capacity map will also be refreshed on a routine basis as data is verified, validated, updated, and maintained to provide an increasingly accurate representation of the system. All these efforts will support streamlining the interconnection process as third-party stakeholders incorporate the hosting capacity map into the early planning phases of a project. This will guide DER developers to submit projects in locations that can more easily accommodate DER assets, which will conserve time and resources for all stakeholders in submitting and processing applications in suboptimal locations.

Ameren Illinois is striding to be a DER enabler, and we are committed to improving and enhancing hosting capacity maps to provide maximum value to all stakeholders while ensuring the safe, reliable, and secure operation of the electrical grid. As previously noted, we anticipate our hosting capacity methodology to mature in alignment with customer expectations and industry trends. We encourage you to contact Ameren Illinois with any questions, concerns, or comments at renewablesillinois@ameren.com.


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