Increasing Demands by Solar Plants for Regulatory Compliance, Efficiency and Productivity Are Met and Exceeded by PACSystems™︎ Control Solutions

Dealing with outdated legacy systems is a challenge for nearly all industrial companies. In the fast-paced solar energy space, shifting market demands, regulatory requirements and increasing competition drive the need for modern capabilities to meet these new challenges. However, upgrading and replacing key technologies can be time consuming and cost prohibitive. This was the challenge that Nor-Cal Controls, a leading solution provider for the renewable power generation industry, faced with two solar power plant customers in the western U.S. While they each had different challenges and considerations, they both required retrofitting to upgrade their technology to meet changes in NERC (North American Electric Reliability Corporation) regulatory requirements and to improve the plants’ efficiency, reliability and productivity.

Solar Power Storage Site Transformation
A 100MWac solar project in California was developed and constructed in 2016 and the company employed a 75MW/300MWh battery energy storage system (BESS) retrofit to the site. The existing SCADA system was not capable of adhering to upcoming changes to regulatory standards as defined by NERC and CAISO (California Independent System Operator), and the system was causing some of the site’s individual inverters to fault and underproduce. Despite over-built site capacity, the control scheme was unable to identify faulted or underproducing field equipment, leading to a loss of revenue. The site’s existing SCADA system needed an overhaul to eliminate underproduction and ensure accurate and predictive fault detection for quick redressal or to prevent faults altogether. Furthermore, the new control system required stringent standards of high availability, cybersecurity, ease of migration and scalability for future expansion.

Nor-Cal Controls redesigned the controls schema for the site utilizing the advanced features in the PACSystems RX3i PLC solution. The updated control scheme consolidated multiple distributed controller tasks into a single, centralized PACSystems RX3i controller, increasing communications reliability and speeding the site’s response time to curtailment instructions or grid instability events. The PACSystems RX3i controller utilizes closed loop controls (PID) to continually compare the plant’s actual vs. command production. This enables the new system to leverage functioning field equipment to make up for the deficits of faulted equipment, thereby decreasing the loss of revenue and increasing contributions to grid stability. With these changes in performance and capability, the system is now fully ready for upcoming CAISO and NERC compliance requirements.

Nor-Cal also selected the PACSystems control solution over other options because of the ease of scalability and ability to integrate with older I/O families. For future migration, the customer just needs to migrate the CPU and retain I/Os, resulting in tremendous savings in cost, testing time and rewiring, and ensuring speed and reliability of migration.

Revamping Control Systems to Prepare for Sale
In another case, the original owner of a 50 MWac western U.S. solar project was seeking to transfer ownership to a new company. The legacy control system, however, was a proprietary software and hardware solution which made the plant less desirable to the potential owner as well as increased the difficulty in transferring operations and maintenance responsibilities to the prospect. The control system needed to be retrofitted, but the project had a limited budget, so the solution had to be scalable and easy to re-engineer and port existing logic and user displays to the new owner, while still being cost effective. This would be in addition to meeting the increasing regulatory compliance requirements from NERC.

Again here, Nor-Cal Controls selected the PACSystems RX3i control solution for the site due to its open architecture and support for multiple protocols. The open design allows the PACSystems RX3i control system to connect to numerous devices, providing operational and diagnostics data. This in turn significantly improved the visibility and control of production metrics from solar panels, string combiner boxes and other devices, increasing the troubleshooting, reporting and diagnostics capability of the plant, and reducing operations and maintenance costs. In addition, since the PACSystems solution can integrate with the existing I/Os, the company saved cost and time.

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