Hawaii Electric Light Company Meets Uptime and Reliability Goals

New process automation system simplifies maintenance and increases flexibility for potential increases in renewable energy resources.

07/12/2012


Hawaii Electric Light CompanyHawaii is known for its beaches, delectable local cuisine, scenic vistas, and opportunities to engage with nature. However, most people don’t consider that Hawaii is also the most isolated island chain on earth, and year-round home to over 1.2 million people who require electricity to live their day-to-day lives on the state’s six main islands.

The “Big Island” of Hawaii is larger than all five of the other islands combined, and is the largest island in the U.S. In fact, with its active Kilauea volcano, it continues to grow in size daily. The island’s residents and businesses—not to mention the tourists—look to Hawaii Electric Light Company, Inc. (HELCO), a subsidiary of the Hawaiian Electric Company, to provide the energy that has transformed the islands from an island kingdom into a modern state.

Challenges of isolation

The Keahole plant is located in Kailua-Kona, Hawaii, the Big Island, and is one of HELCO’s primary power-production facilities and the largest plant on the island. It features three combustion turbines that generate approximately 240 gigawatt-hours of energy each year, which represents almost one-fourth of the entire power-generation capacity available on the island.

Unfortunately, in 2006, the company was faced with upwards of 50% downtime caused by the control system that was supplied with the turbines. “The original turbine control system was completely proprietary, and by 2006, also entirely obsolete,” said Norman Verbanic, HELCO’s production department manager. “Replacement parts were essentially nonexistent. When something failed that we couldn’t fix ourselves with a repaired card, flying in a controls engineer to troubleshoot the system could cost tens of thousands of dollars.”

Indeed, because of HELCO’s isolated location, repair parts could take more than two days to arrive. Flying in controls engineers from other countries could take even longer. The inevitable result was that the Keahole plant was at reduced capacity nearly 50% of the time. “In order to improve our uptime rates, we knew we needed a new turbine control system with an open architecture that our maintenance staff people could troubleshoot and optimize themselves, without having to rely on outside expertise,” explained Verbanic.

In 2008, the state of Hawaii and the Hawaiian Electric Company crafted an energy agreement that requires 40% of electricity needs and 70% of overall energy needs (including transportation) to come from clean, renewable sources by 2030. While these requirements far surpass mainland renewable requirements, Hawaii’s abundant natural resources, including sun, wind, hydro, and other renewable resources, render it a perfect candidate to lead the charge in renewable-energy generation. “Long term, we’re hoping to have the entire Keahole plant producing power from locally raised biodiesel,” said Verbanic.

Using the new system, the Keahole engineering staff has an easier time troubleshooting operational problems, Courtesy: HELCOAn adaptable solution

Once Verbanic and his team made the decision to replace their obsolete turbine control system, they settled on the Rockwell Automation PlantPAx process automation system. Based on the Rockwell Automation Integrated Architecture platform, the system delivers a unified process, discrete, and information solution. The entire system is configured using Rockwell’s RSLogix 5000 software and communicates to I/O inputs via ControlNet, and third-party operator interfaces via an EtherNet/IP network.

“We looked at other traditional DCS vendors, but they each had proprietary, closed systems and expensive spare parts, maintenance, and support contracts,” said Verbanic. “We couldn’t afford that in terms of expense or time—especially not at our remote location. We were familiar with Rockwell Automation products and knew we could troubleshoot, maintain, and optimize the PlantPAx system ourselves.”

The Wood Group, a Rockwell Automation PartnerNetwork recognized system integrator headquartered in Loveland, Co., was contracted to install the new turbine control system. “We benchmarked the PlantPAx system against all other DCS systems in order to prove it was capable of handling the high bandwidth and rapid execution rate requirements that high-speed, aeroderivative gas turbines demand,” explained Clark Weaver, project manager, Wood Group Controls.

At the Keahole plant, Wood Group engineers left the original I/O from the previous control system in place but removed the original processors that caused so many issues previously. “Our original system was triple-redundant, with three separate processors and I/O cards for each turbine,” explained Verbanic. “With the new system, we’ve leveraged the original triplicated I/O field devices and matched them with new triplicated I/O modules streamlined to simplex PlantPAx processors. This helped protect process uptime should something fail unexpectedly while significantly simplifying the system architecture.” The PlantPAx processors were also equipped with redundant parallel power supplies for enhanced reliability.

In addition, Allen-Bradley XM condition-monitoring modules monitor vibration on each turbine and generator. This helps identify potential problems before they reach a critical level. Information from each XM module is transmitted back to the central control system for improved, real-time turbine health monitoring and predictive maintenance. Wood Group engineers also implemented an Allen-Bradley Combined Generator Control Module (CGCM). The duplexed CGCM integrates with the PlantPAx system to provide digital power metering, voltage regulation, and automatic synchronization control for each of the turbines. Thanks to the redundant configuration, it also enhances system reliability.

Results

Verbanic and his team found that with the old turbine control system, the question wasn’t when the plant would start up, but rather if it would start up at all. “With the PlantPAx system, we know the controls are running whenever we need them,” he said. In fact, turbine controls-related downtime at the plant dropped from a high of around 50% to less than a few percentage points annually since the system upgrade. And when a rare control problem does occur, it is quick to troubleshoot and resolve, without having to cross-reference cryptic codes and acronyms.

Based on the track record built over three years, when the HELCO team decided to convert the Keahole facility to a combined-cycle plant, it was a relatively simple matter simply to expand the new platform. “With our great success on the turbine retrofit project, we knew we wanted to utilize the PlantPAx system for plant-wide control as well,” explained Verbanic. “We were looking for a flexible system that would allow us to accommodate fluctuations in demand and knew it could do exactly that.”

Mustang Engineering, a Wood Group company, was contracted for the project and helped expand the platform to cover the entire facility. “The power generation industry is asking for a flexible, reliable, open-control platform,” said Weaver. “On the turbine project, we proved that with the right engineering expertise, the PlantPAx system is exactly that. Based on that success, we also proved that it was a viable alternative to traditional DCS platforms for plant-wide control as well.”

Now, the system controls almost every aspect of the Keahole plant, including the turbines, heat recovery boilers, generators, water treatment, steam turbine, and emissions systems, as well as most balance-of-plant applications. Verbanic and his operations and maintenance teams benefit from significantly simplified maintenance, operability, and troubleshooting by using a single hardware and software environment for the entire facility.

“Replacement parts are easy to obtain and cost-effective to keep in stock, and our staff is more than capable of identifying and solving any problems that arise, no matter where the problem may be located in the plant,” said Verbanic. “In fact, they’ve been able to identify opportunities to optimize the system entirely on their own. They’ve really been able to focus on becoming experts on the PlantPAx system.”

With significant improvements in turbine availability and plantwide control on a single open platform, the staff at HELCO feels far more self-sufficient. “It’s been a really pleasant ride,” said Verbanic. “Since each island is an autonomous grid without interconnections to neighboring island utilities, we cannot rely on the outside world to keep the lights on. With the robustness and flexibility of the Rockwell Automation solution, we do exactly that.”

Ben Mansfield is PlantPAx marketing manager for Rockwell Automation.