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Generating Electricity from Variable Renewable Sources: Effect on the Grid

Mark P. Rossow, PhD, PE Retired


Course Outline

This six-hour online course begins by describing the physical and operating characteristics of the existing electrical grid.  Then the course considers how the operation of the grid will be affected when variable renewable energy sources, such as solar and wind, are introduced into the system.  Actual operating experience to date indicates that it is technically feasible to operate an electric power system with wind energy penetrations of 10%–20% of energy generated, albeit with changes in current operational practice to provide increased flexibility and expanded cooperation over longer distances. However, operating challenges are leading to curtailment of wind plant outputs during periods of low system demand or transmission congestion. The course concludes with the observation that not only must operating procedures evolve to better accommodate variable resources, but also market transformations must ensure appropriate payments for needed energy, capacity, and ancillary services.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

This course teaches the following specific knowledge and skills:

Intended Audience

This course is intended primarily for engineers concerned with the use of solar and wind energy to produce electrical energy.

Benefit to Attendees

A person completing this course will be sufficiently familiar with variable-energy/electric-grid issues to be able to interact knowledgeably with specialists in the field.

Course Introduction

The electric power system is the infrastructure that converts fuel and energy resources into electric power (thus generating electricity) and carries and manages that electric power from where it is generated to where it is used. It is a system of systems that comprises physical networks that include fuel and resources; power plants of many different varieties; electric transmission and distribution line networks and measurement; information and control systems; and virtual networks of money, business relationships, and regulation. Achieving balance among all of these elements is a fundamental challenge for the planning, engineering, and operation of the overall system because of the variability and uncertainty of load and unexpected equipment failures that affect the generation and delivery of electricity. The system of systems is loosely referred to here as “the grid.”

Course Content

This course is based on Volume 4: “Bulk Electric Power Systems: Operations and Transmission Planning.”  Milligan, M.; Ela, E.; Hein, J.; Schneider, T.; Brinkman, G.; Denholm, P. (2012).  Exploration of High Penetration Renewable Electricity Futures.  Vol. 4 of Renewable Electricity Futures Study.  NREL/TP-6A20-52409-4. Golden, CO: National Renewable Energy Laboratory.

Renewable Electricity Futures Study. NREL/TP-6A20-52409-4

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Course Summary

Renewable electricity is available from a very diverse set of resources and technologies. Some are dispatchable (the electricity generation can be started or stopped at the request of the grid operators), and others—primarily wind and solar PV technologies—are generally nondispatchable in that system operators can curtail output but cannot increase it if the wind or solar resource is not available. Both wind and solar PV technologies present challenges to power system operators, owing to variability and uncertainty of their generation output on the timescales relevant to the task of maintaining system reliability. However, generation from these variable renewable resources is being added to the electric system now. In particular, wind generation is expanding rapidly in some regions of the United States. As a result, significant operational challenges are emerging, including curtailment resulting from transmission and minimum generation constraints, relatively rare rapid ramps in wind generation resulting from passage of large footprint storm fronts, and increased need for operational reserves due to uncertainty of generation output.

Related Links

For additional technical information related to this subject, please visit the following websites or web pages:

http://www.eere.energy.gov/topics/renewable_energy.html


Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.