Maintaining System Reliability with Added Generation

Guidehouse helped NorthWestern Energy determine flexibility requirements to accommodate new wind generation


Northwestern Energy (NWE) has more than 3,000 MW of new wind generation in its interconnection queue. The utility company engaged Guidehouse Inc. to determine flexibility requirements sufficient to maintain system reliability as generation is added to the system.



Guidehouse used its proprietary STORM model to complete sub-hourly simulation of the NWE system under several renewable penetration scenarios. The modeling results showed the amount of ancillary services, such as regulation and load following, that would need to be increased to maintain the system simulation. The analysis also showed the benefits that geographical diversity can bring to integrating renewables. NWE will use the results to determine how to allocate system costs to different participants and also to provide information to renewable generators that may self-supply integration services.



The Guidehouse approach provided NWE with a clear, transparent methodology for what resources are needed to maintain the system that can be used to continue to monitor the impacts of the energy system transformation. NWE has gained confidence in what resources are necessary to maintain system reliability as intermittent resources are added. Guidehouse is also supporting NWE with testimony to explain the results to the regulatory commission.

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