Standardizing weather data: a sunny forecast

.

By Pat Brown, EPRI

Henry Dotson, Southern California Edison

Alan McMorran, Open Grid Systems

Weather, good or bad, is a pervasive and ever-changing influence on the electrical system.  Temperatures and humidity drive load, storms damage distribution lines, sunshine powers photovoltaic panels, icing topples trees into service drops and makes restoration challenging, floods threaten riverside power plants, wind turns the turbine blades at wind farms and earthquakes damage equipment and disrupt crew mobilization.

For decades, utilities have used weather information to help predict, manage and respond to the effects of weather on the electrical grid.  Today, utilities routinely utilize weather information from a variety of sources and service providers.  Some sources are better at forecast data, some at historic; some sources provide numeric data, some visual; some specialize in one type of data, such as current cloud cover, some in other types of data, such as forecast temperature or hurricane warnings.  And the data arrives in a variety of formats, often requiring in-house processing or custom software interfaces to make the information useful to the utility.

Two initiatives currently underway seek to standardize the exchange of weather data within the electric utility environment and simplify the process of providing weather data to software applications that require it.  The projects are being sponsored by the NIST SGIP Building to Grid Domain Expert Working Group, (B2G DEWG), and by Southern California Edison (SCE) jointly with the Electric Power Research Institute (EPRI).   While the B2G DEWG effort focuses on the effects of weather on facilities that consume electricity and the SCE/EPRI project approaches the problem from a utility perspective, both projects are relying on use cases to drive requirements, are identifying and evaluating existing weather standards and ultimately seek to provide a standardized weather data model that is sufficiently robust for widespread electric utility industry adoption.

A large number of weather data-related use cases have been identified by the two projects. Some examples, which are common across the industry, include:

·         B2G DEWG - Forecasting of near, medium and long term power needs; Managing and protecting distributed energy resources; Optimizing start/stop times; Determining timing of building load shifting, among others.

·         SCE/EPRI - Creating real-time and study load forecasts; Approving software deployment; Scheduling planned outages; Planning energy trading; Modeling distribution power flow; among others. 

Data modeling work is underway on both projects.  As a starting point for modeling, the SCE/EPRI project has organized weather information into the following classifications:

Weather Data Environments

®  Atmospheric (for example: humidity, precipitation, air temperature, wind, lightening)

®  Geospheric (earthquakes, mudslides)

®  Hydrospheric (tides, tsunamis, wave heights, water temperature)

®  Space (solar flares)

Weather Data Time Periods

®  Forecast

®  Current

®  Historic (including historic forecasts)

Weather Data Categories

®  Measured (raw data measured by an instrument)

®  Condition (evaluated data like icy conditions, partly sunny skies)

®  Advisory  (tornado watch, flooding warning, winter weather advisory)

A critical component of the modeling process is the evaluation of existing weather standards and standardization initiatives, which is being done with two intents: augmenting the weather standards to include utility specific information and harmonizing the weather standards with existing utility industry standards like the Common Information Model (CIM) and 61850.  Weather community standards that are currently being examined include the Weather Data Model (WXXM), a UML-based structural definition for the exchange of information designed by U.S. and European air traffic control organizations (FAA and Eurocontrol), and the Typical Meteorological Year 3 (TMY3) format.

The goal of both projects is interoperability and both projects are based on the recognition of the benefits and efficiencies to be gained from standardizing weather data exchange in the electric utility space.  For more information or to contribute to these undertakings, contact:

B2G DEWG -    David Holmberg (NIST) david.holmberg@nist.gov

SCE/EPRI -       Henry Dotson (SCE) henry.dotson@sce.com

Pat Brown (EPRI) pbrown@epri.com

Alan McMorran (Open Grid Systems) alan@opengridsystems.com