SmartGridCity™

A consortium of Smart Grid solutions vendors – representing every major facet of the distribution grid – has partnered with Xcel Energy to design and implement its vision of a fully connected and horizontally integrated system that identifies all aspects of the power grid and communicates its status and the impact of consumption decisions.

SmartGridCity™ integrates intelligent sensors, distributed communications and analytical control applications from the substation to the customer premise, enabling a host of high value applications. These applications are expected to provide significant utility and customer benefits including improved service reliability, reduced operations and maintenance costs, optimized system losses, reduced capital costs, better managed renewable energy resources, and reduced customer energy demand.

CURRENT Group, LLC, one of the partners in the SmartGridCity™ consortium, has provided the infrastructure and applications to enable Xcel Energy’s vision, including:

• A robust, two-way, low latency communications network that incorporates fiber optics, 3G cellular wireless, MV/LV broadband over power lines and DSL to provide connectivity throughout the distribution system to approximately 45,000 premises in Boulder, Colorado
• Intelligent voltage and current sensors located at distribution transformers that provide the edge analytics for the distribution system
• OpenGrid™, CURRENT’s standards-based open software platform,  manages the communications network and provides standard interfaces to utility devices and utility back office systems with a robust relational and spatial database to enable high valued analytical and control applications
• Automated Metering
• Integration with a number of Demand Response technologies 
• A rich set of analytical and control applications including:
     o Incipient Transformer Failure Detection
     o Transient Voltage Disturbance Analysis
     o Voltage Imbalance Analysis
     o Transformer Overload Detection
     o Remote URD Fault Indication
     o Outage & Restoration Detection
     o Integrated Volt/VAR Control
     o Instant Meter Reading
     o Daily Meter Collection

These applications are in production in Boulder, CO, and Xcel Energy is working towards integrating their capabilities into its back office systems, and incorporating its features into standard business processes.

Case Studies
Monitoring of voltages and currents at distribution transformers enables a number of valuable Distribution Management applications that improve service reliability, reduce customer complaints, and lower operations and maintenance expenses through the delivery of “Actionable Intelligence™.”   For example, in the case study presented below in Figure 1, the data appeared initially as a Low Voltage anomaly, which triggered a notification to the Xcel Energy area engineer responsible for Boulder, CO.

Figure 1 – Voltage measurements which triggered Low Voltage Notification

Upon receiving the Low Voltage notification set forth below in Figure 2, the area engineer was able to perform additional analysis of the issue utilizing loading information that is also available from the SmartGridCity network.

Figure 2 – Transformer Loading concurrent with Low Voltage Notification

By analyzing these measurements concurrently and reviewing recent loading and voltage history at this transformer, Xcel Energy determined that the cause of the low voltage was the overloading of the transformer.

A final case that provesthe value of distributed sensing is the detection of open neutral conditions. These conditions are common on the secondary system and cause voltage complaints, customer equipment damage and can lead to shock hazards. Using traditional methods, open neutrals are detected by customer complaints and are time consuming to locate and correct. The case study presented below in Figure 3 starts with the notification that a problem was detected.

Figure 3 – Smart Grid Report Dashboard

Following the link from the Secondary Neutral Failure alarm, the Area Engineer is able to view the measurements that initiated the notification. The voltage chart, as exhibited in Figure 4, displays that the two 120-volt legs are varying in a mirror image of each other, indicating an open secondary neutral.

Figure 4 – Open Neutral Voltage Variation

In this case, Xcel Energy found a loose connection that was tightened to correct the problem, before any customer complaints or customer equipment damage occurred.

The case studies above reflect a simplified view of the beginning of the benefits and applications that Xcel Energy will receive as it implements and operates the world’s first SmartGridCity. Through the efforts of Xcel Energy’s Consortium Partners the operation and implementation of SmartGridCity will provide more benefits as the value of the Smart Grid network increases through the addition of new applications and services.