T&D World Magazine
Grid Modernization at APS

Grid Modernization at APS

Arizona Public Service is pretty vocal about its support for flexible grid technologies, so not surprisingly, peers in the industry ask why. There are five reasons why APS “got off the fence” more than five years ago and began implementing flexible grid technologies to respond to a transforming marketplace. APS identified appropriate flexible grid technologies by evaluating the elements of change:

  • Customers seeking greater energy independence through newly available choices such as self-supply, electric vehicles, microgrids and demand response.
  • Technology advancement. The transition both on the utility and customer side to digital equipment, advanced applications of microprocessors, battery storage, wireless devices and cloud computing is accelerating.
  • Asset utilization. Customers and utilities are rightly motivated to increase asset life, improve capacity factors, reduce losses and increase efficiencies.
  • Performance. Customers have higher expectations regarding outage response times, power quality and availability of system information.
  • The pace of communication. Customers expect instant information about outages, electric usage, bill status and rate plans.

All considered, the need for dramatic change is almost a forgone conclusion for most traditional distribution systems. The importance or prevalence of the five elements at play in a utility’s service territory may dictate the recipe required for grid modernization. Also, just because one forward-thinking utility is implementing a particular upgrade, does not ensure it is the right recipe for others. Factors such as solar radiance, topography, geography, customer makeup and regulatory climate require consideration in order to best serve one’s customers and remain competitive in the new world.

The Recipe for Change Response

To build its flexible grid program, APS selected five foundation technology components: energy management systems (transmission), advanced distribution management systems (ADMS; distribution), advanced meter infrastructure (AMI) communications infrastructure and advanced analytics. A major driver for APS is Arizona’s solar radiance, which is very high, even by global standards. APS went from less than 200 solar customers in 2008 to more than 42,000 today. The impact on the distribution system has been incredible. Now with feeders containing hundreds of solar generation sources, and reversed power flows at times, APS must maintain power quality, reliability standards and voltage dynamically throughout the day. The answer for APS was new technology that delivers visualization and automation.

Not Once and Done

APS uses a five-year rolling window with benchmarks to evaluate if it is moving fast enough and its chosen foundational technologies are still correct. APS’s distribution operations and maintenance function has benefited most by installing communicating fault indicators, supervisory control switches with strategic conversions to self-isolating systems and two-way communications to capacitor banks with strategic conversions to integrated volt/var control. AMI has resulted in significant operational benefits given APS’s mix of seasonal and time-of-use customers. Now customer usage data can be aggregated to get load profiles on secondary distribution transformers and analyze voltage on feeders. Then, with two-way control of cap banks and line regulators to dynamically control voltage, the system can be optimized to handle more renewable generation and perform with improved power quality.

APS started its grid modernization effort using pilot programs that allow experimentation and customization. Pilots help reveal what processes, procedures, skill sets and staffing levels must be altered. Many of the new technologies need more communications network and security architects, more software inventory and different commissioning and operations strategies. Change management involving operators and unions is needed so everyone sees the benefits of the new tools.

A new ADMS system with central control and data storage was selected to fully utilize all the data analytic capabilities and move from schedule-based to condition-based maintenance. APS advises new implementers to start small and build foundationally based on major drivers affecting one’s utility. To do otherwise will overwhelm a company on a cost and change management basis. Annually refresh the modernization plan to catch market shifts or other changes.

Looking Forward

The future will continue to bring changes on the utility and customer side. Energy storage or a step change in the cost of solar or some new technology may be the next game changer. Utilities with a strategically drafted grid modernization program underway should be able to react more quickly and continue to provide the greatest value to their customers.


Tony Tewelis ([email protected]) is director of distribution operations and maintenance at Arizona Public Service.

TAGS: Smart Grid
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