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The bulk power system is undergoing a digital revolution. With the recent and continuing growth of inverter-based generation, primarily wind and solar energy, the industry has begun exploring the implication of these new resources on power system reliability and resilience. This paper provides an overview and description of grid services that key resource types are able to provide, showing that new resources can provide many of the required grid reliability services.

This paper discusses the importance and challenges of incentivizing flexibility during short-term operations of the bulk power system due to the increasing variability and uncertainty from growing penetrations of variable generation (VG). Operational flexibility can refer to many aspects of a resource’s capability to support the power system, such as the speed, range, and duration of power output, as well as the ability to autonomously respond to frequency or voltage changes. Inefficient utilization of existing flexibility, or unwillingness of resources to provide flexibility, can compromise system reliability by not meeting the changing net load, and it can also lead to higher costs when an inefficient use of flexibility resources occurs. There are many existing characteristics of market design that incentivize flexibility in some manner. How they incentivize the provision of flexibility as well as the level of flexibility is still debated. We explore some of these existing market designs, as well as new market mechanisms, such as pay-for-performance regulating reserve and flexible ramping products, that aim to explicitly incentivize the provision of more flexibility to the system, particularly as a result of increasing VG penetration levels.

This paper discusses challenges that relate to assessing and properly incentivizing the resources necessary to ensure a reliable electricity system with growing penetrations of variable generation (VG). The output of VG (primarily wind and solar generation) varies over time and cannot be predicted precisely. Therefore, the energy from VG is not always guaranteed to be available at times when it is most needed. This means that its contribution towards resource adequacy can be significantly less than the contribution from traditional resources. Variable renewable resources also have near-zero variable costs, and with production-based subsidies they may even have negative offer costs. Because variable costs drive the spot price of energy, this can lead to reduced prices, sales, and therefore revenue for all resources within the energy market. The characteristics of VG can also result in increased price volatility as well as the need for more flexibility in the resource fleet in order to maintain system reliability. We explore both traditional and evolving electricity market designs in the United States that aim to ensure resource adequacy and sufficient revenues to recover costs when those resources are needed for long-term reliability. We also investigate how reliability needs may be evolving and discuss how VG may affect future electricity market designs.

Six examples of transmission planning scenarios in which simplifications impact the modeling results can provide useful insights to non-technical participants in transmission planning. Because of modeling simplifications and future uncertainties, no single model can capture all aspects of transmission expansion planning. Instead, sensitivities and trends should be compared across multiple models and the results combined with broader contextual information.

Frequency responsive reserve is the autonomous response of generators and demand response to deviations of system frequency, usually as a result of the instantaneous outage of a large supplier. This article discusses the issues that can occur without proper incentives and even disincentives, and proposes alternatives to introduce incentives for resources to provide frequency responsive reserve to ensure an efficient and reliable power system.

This article examines how wind and solar integration studies have evolved, what analysis techniques work, what common mistakes are still made, and what and why calculating integration costs is such a difficult problem that should be undertaken carefully, if at all. Examples of integration costs for other generation technologies are examined to help illuminate underlying cost causation principles.

Wind integration will not be accomplished successfully by doing “more of the same.” It will require significant changes in grid planning and operations, continued technical evolution in the design and operation of wind turbines, further adoption and implementation of wind forecasting in the control room, and incorporation of market and policy initiatives to encourage more flexible generation.

When wind plants serve load within the balancing area, no additional capacity required to integrate wind power into the system. We present some thought experiments to illustrate some implications for wind integration studies.

This paper evaluates which wholesale elecricity market-structure characteristics best accommodate wind energy development.

As more wind energy capacity is added in the nation, the question of wind's capacity value is raised. This article shows how the capacity value of wind is determined, both in theory and in practice.

Energy imbalance provisions in open access transmission tariffs pose a formidable obstacle for commercial wind energy development in the U.S. To allow wind project development to proceed, some ISOs have adopted provisions reflecting the variable nature of wind energy resources.