September 2, 2017 | Jessica Cropley & Scott Grafelman
Many utility organizations are wondering if their Supervisory Control and Data Acquisition (SCADA) are really in a state that will be beneficial or even adequate for Distributed Energy Resources (DER) management. Over time, SCADA systems will become even more important, because they allow the utility to manage potential negative impacts of DER installations, as well as leverage opportunities to improve reliability. To take full advantage of SCADA systems, the data must be available; utilities must be confident in its accuracy and, in the end, be able to see it in a form that is actionable by grid operators. Let’s explore some of the key factors and things to consider as you prepare for the future.
Communication with SCADA Devices Mitigates Downtime
Gathering data from SCADA field devices is dependent on getting the data back to the central master data collection point. Missing data leaves voids in the analysis, and reduces visibility into what’s going on in the field. This real-time communication between field devices and the SCADA master can yield hundreds to thousands of data points every day. Storing these data points in a historian system allows for metrics and analytics to be created downstream.
The quality of the SCADA communications system can be viewed as ‘availability’; if a field device is communicating with SCADA, its status will show as “good” or available. If the device is not communicating, the status will show “unavailable”. Availability of SCADA data can be determined by calculating the amount of time a point is communicating with the SCADA system correctly:
Seconds in “good” status per day
———————————————- x 100 = Daily Availability %
86,400 seconds per day
This calculation is the foundation for producing analytics for SCADA data. These percentage values can be shown on a daily basis for each point, rolled up into a hierarchical level (Device, Circuit, etc.), and/or shown on a trend graph over a selected time period. The ability to view the availability of all the points, rolled up into a single device, allows users to understand how the communication is performing within the SCADA system, as well as where changes are occurring. A collection of communication pings can be used to open the doors to troubleshooting and hardware improvements, but only if the metadata of the points is available and consistent.
Faulty communications are unscheduled events that will negatively impact the availability of your SCADA data; they should be corrected to maintain high availability. Planned outages and scheduled switching operations are two examples of daily grid operations that should be removed from the calculation, so as not to skew the availability calculation.
Good Data In, Good Analytics Out
Accurate and consistent data is essential to any data-driven system. Without data standards and data accuracy checks, utilities cannot trust that their data is organized and presented accurately. Data accuracy, or reasonableness of the data values received, should be checked constantly. Data that is out of the boundary of an expected value should be flagged for investigation.
Data gaps can exist across the various OT systems used to manage the grid. A data assessment and cleanup effort, prior to attempting to use SCADA data for analytics, will greatly increase the success of the project utilizing the data. Be aware, however, that SCADA metadata quality problems are present in data collections, files, and databases, due to errors like misspellings during data entry, missing information, and invalid/incorrect data to name a few. With each system that is added and/or integrated, the effort to address this issue becomes more significant. To address these problems, utilities must also consider the following:
- Data redundancy, which can introduce duplicate metrics used in the analytics.
- Inconsistent naming conventions, which can potentially result in the inability to tie critical metadata.
- Incomplete views of a particular device, which are an effect of data shortcomings.
Needless to say, consolidating data sources, and adhering to strict data quality and consistent naming standards, are essential to providing quality data for downstream analytics.
Visualization is Key
Scrolling through page after page of source data is not only time-consuming but provides little value when trying to determine the health of your SCADA data. You wouldn’t want your accountant to send you a file of transactions to determine how you’re doing financially; it’s far more efficient for you to receive a summary report containing targets, totals, and trending. Utilizing a visualization platform, such as a dashboard or reporting tool, will give utilities insight into the health of SCADA data, and enable more informed decisions about future improvements.
SCADA data dashboards and reporting tools provide the ability to roll-up SCADA data into an organized hierarchy; this allows you to view trending by geographical locations, equipment types, regions, etc. A good dashboard will present analytics and metrics in ways that are easy to understand, such as consistent formatting, standard color statusing, and intuitive navigation. Summary views containing high-level metrics are useful for leadership reporting and meetings (See Figures 1 & 2), while detailed views are useful for day-to-day reporting and troubleshooting. (See Figures 3 & 4)
Figures 1 and 2 illustrate examples of high-level summary dashboard views (overall summary and substation summary). Figures 3 and 4 illustrate low-level detailed views of a specific device and real-time PI Point quality values that make up the availability calculation.
Demands on grid operators are increasing with the availability of more OT systems that manage and integrate the increasing number of DER installations: SCADA, Distribution Management Systems (DMS), and (particularly) Distributed Energy Resource Management System (DERMS). This results in a flood of data that operators need to evaluate and respond to, for optimal grid performance. By ensuring that operators have all the available data, as accurate as possible, and presented in a meaningful and organized display, they will be able to make better and timelier business decisions. These decisions are critical to maintaining safe, economical and reliable electric service.