Summer peak influences grid investments, rate design

June 22, 2016

Right on cue, summer is blazing in this week with record-setting temperatures. It’s also creating near-record energy consumption by our customers, who are trying to stay cool while keeping their homes and businesses running smoothly.

Energy demand on the APS system peaked between 5 p.m. and 6 p.m. on Sunday, June 19 and Monday, June 20 at more than 7,000 MW, close to last year’s peak of 7,060 MW, set on Aug. 15.

These days when demand climbs to its highest levels are important for two reasons. First, we must build the grid to maintain reliability and provide the entire energy infrastructure needed to meet customers’ demand. This influences decisions about the investments we make in the energy grid.

Secondly, we look for ways to reduce peak usage, which in turn can limit costs in the long run. That’s one reason why we proposed widespread adoption of demand-based rates in the current rate review.  Demand rates encourage customers to reduce their peak usage during high-demand times, which lessens strain on the grid and enhances reliability.

 APS energy grid by the numbers  
 Distribution power lines 29,148 miles 
 Transmission power lines 6,119 miles 
 Power poles 420,000+ 
 Transformers 300,000+ 
 Substations 430 
 Power generation units
(owned, leased and renewable PPAs)

In addition to ensuring the grid is large enough to accommodate customers’ needs, we also make investments to operate it more efficiently. One is Project Illuminate, a state-of-the-art grid management system that will enhance safety, efficiency and customer value. The project’s cornerstone is the Advanced Distribution Monitoring System (ADMS). The system will enable operators to diagnose potential trouble spots on the energy grid in real time and enhance response to outages.

Jacob Tetlow, APS General Manager of Transmission and Distribution (T&D) Operations and Maintenance, writes in his Rate Review testimony that ADMS “will combine a base distribution operating platform, outage management system, advanced engineering applications and distribution equipment control system in one integrated operating platform. These systems, working together, will allow APS to perform advanced engineering and analytics on the system, and provide our system operators with industry-leading functionality.”

The APS predictive maintenance group identifies issues before they impact customers, like this transmission line "hot spot," using specialized infrared imaging cameras.

We also deploy technology in the field to head off potential infrastructure problems before they create issues for customers. Our predictive maintenance program uses vehicle-mounted infrared equipment to locate “hot spots” on the energy grid. These hot spots can be indicators of energy delivery components such as transmission and distribution wires wearing out. APS crews then further inspect the equipment and replace items as needed.

Besides using advanced technology to support the energy grid, we are strengthening it against weather disruptions with equipment like “stopper” poles. The heavily reinforced steel poles are spaced among other poles to prevent longer stretches of poles from toppling during high monsoon winds.

These are just a few examples of the investments we are making to provide our customers with a cleaner, stronger and smarter system to meet Arizona’s changing energy needs.