Creating High-Speed Electrical Analysis for Energy Research

The Energy Systems Integration Facility (ESIF) at the National Renewable Energy Laboratory in Golden, Colorado. Image courtesy of NREL.

By Nick Aroneseno and Craig Eidson, Optimation

Optimation provides complete engineering, automation, construction and maintenance services for a variety of industries including renewable energy. As a Gold National Instruments (NI) Alliance Partner with more than 27 years of experience, Optimation was invited to propose a solution to the National Renewable Energy Laboratory (NREL) for distributed power monitoring within the Energy Systems Integration Facility (ESIF). Optimation’s Colorado office, which opened in 2010, gave NREL quick access to qualified resources for the project.

NREL scientists and engineers research renewable energy and energy-efficient technologies, often partnering with private industry to deliver these ideas to the general public. NREL designed the ESIF to facilitate groundbreaking research in areas such as solar and wind, grid planning and operations, energy storage, building technologies, fuel cells and advanced vehicles. Each lab at the 182,500 sq. ft. facility is designed and instrumented to foster research on all aspects of energy systems integration. Some of the unique capabilities of these labs include the ability to perform hardware-in-the-loop (HIL) simulations at megawatt-scale power, petascale computing at the High-Performance Computing Data Center, and the unique Research Electrical Distribution Bus (REDB). Monitored with CompactRIO, REDB is the ultimate power integration circuit. It consists of two AC and two DC ring buses that interconnect multiple sources of energy across the facility, enabling NREL to work with industry to provide plug-and-play testing at grid-scale levels.

Since the ESIF is intended for researching various forms of energy integration, NREL researchers needed a system for monitoring power usage and controlling safety systems for each experiment or laboratory on a facility-wide scale. Monitoring AC and DC power loads can provide researchers with power usage information for their individual experiments and allow facility managers to view the total energy usage on a facility-wide or laboratory-by-laboratory basis. An additional benefit is the safety monitoring for laboratories in the event of dangerous electrical conditions caused by experiments, ultimately protecting the researchers and facility equipment.

The REDB is the electrical backbone interconnecting many of the laboratories at ESIF. This state-of-the-art facility will enable NREL and industry to work together to develop and evaluate their individual technologies. Image courtesy of NREL.

Researchers needed a power monitor they could configure on an individual experiment basis for multiphase AC and DC measurements. They also needed a power meter they could use to configure the meter to mimic multiple types of circuit breakers while analyzing power characteristics such as real power, reactive power and energy. To enable live analysis of complex energy experiments, researchers required high-speed and high-resolution data (16-bit, 50 kS/s). Furthermore, the power monitor needed to communicate to various third-party human machine interfaces (HMIs) and programmable logic controller (PLC) devices from Wonderware and Siemens. A power monitor capable of providing all of these features did not exist in the market. As a result, Optimation was hired as a subcontractor to NREL to develop such a device for the ESIF.

Solution Details

Optimation provided software images for more than 70 CompactRIO units installed within electrical panels throughout the ESIF. Optimation’s solution is responsible for monitoring electrical conditioning components between the ESIF’s power sources (120 V, 240 V, 480 V, 600 VAC, and 1,000 VDC on 250 A and 1,600 A busses) and the laboratory power connections. As a result, any powered device under test or equipment used for testing in the lab was actively monitored by CompactRIO. Voltage transformers bring voltage levels intoa range compatible with the NI C Series devices in use and protect equipment from excess voltage.

The team considered using traditional PLCs during preliminary phases of the project; however, it became apparent that the system performance requirements, including the high sample rate and near real-time processing, would be too much for this traditional form of hardware. Instead, Optimation selected the NI system design platform, including CompactRIO hardware and LabVIEW software, because of the flexibility and deterministic timing capabilities of CompactRIO and the diverse offering of high-performance I/O modules.

Optimation used systems based on the NI cRIO-9024 embedded real-time controller with the NI cRIO-9118 backplane and the NI cRIO-9082 controller for this project. To monitor, analyze, alarm and communicate, the CompactRIO devices were programmed using the LabVIEW Real-Time and LabVIEW FPGA (field-programmable gate array) modules. This allowed the system to deterministically perform each of these functions in parallel threads. With data being acquired at more than 50 kS/s, Optimation implemented the CompactRIO Waveform Reference Library to efficiently transfer high-speed data from the FPGA to the real-time application.

Several components of this NI-based solution were critical to the project’s success. First, the LabVIEW FPGA Module made it possible to implement a system responsible for identifying unsafe electrical conditions and reporting these conditions back to the control systems. Second, simultaneously sampling data across input channels using the NI 9215 analog input module, combined with the accuracy of the NI 9467 GPS module, made timing synchronization between CompactRIO devices accurate within 100 ns. This was especially beneficial when correlating data from multiple laboratories, where testing areas are separated and monitored by different CompactRIO devices. Third, with the processing power of the CompactRIO real-time controllers (800MHz and 1.33GHz), the systems acquired and processed 28 channels at 51,200Hz while managing other functions, such as alarm monitoring and TCP/IP and Modbus communications.

The REDB for AC and DC testing at the new ESIF, which includes CompactRIO hardware is pictured. Image courtesy of NREL.

Optimation developed and compiled more than seven custom FPGA bitfiles for this project. The individual compile time for each FPGA application averaged 1.5 hours. Furthermore, prior to releasing final versions of the FGPA applications, several preliminary compilations were necessary to account for project scope changes and shifting requirements. To counter this, Optimation used the LabVIEW FPGA Compile Cloud Service to compile the FPGA applications, which saved valuable developer time on the project. With the LabVIEW FPGA Compile Cloud Service, developers could push multiple FPGA builds to an external server managed by NI, compile code in parallel, free up developer machines for other tasks, and drastically shorten compile times (2.6 to 5.3 times shorter).

Solution Benefits

Overall, the Optimation solution delivers the following benefits:

• High-speed data acquisition, which provides a more accurate representation of the effects individual experiments may have on the grid;
• Correlated data from synchronized systems distributed throughout the ESIF, enabling researchers to better understand multilab experiments and characterize the building’s electrical profile;
• Easily reconfigurable virtual power meters and CompactRIO systems that can be configured as AC or DC devices without recompiling or reimaging the controllers;
• A transparent and flexible architecture for future expansion, including features to send data to third-party systems through standard communication protocols such as TCP/IP and Modbus;
• Safe emergency-stop monitoring, implemented in dedicated FPGA code;
• And dynamically configurable analysis algorithms (virtual metering objects), enabled by the deterministic real-time processing capability of CompactRIO hardware for analyzing electrical characteristics for safety violations and in simulating complex circuit breaker logic.

Project Conclusions

Using CompactRIO and LabVIEW, Optimation quickly developed a prototype and responded to customer questions and expectations for a distributed power monitoring solution. Changes in scope and requirements as a result of discoveries made mid-project had minimal effect on the schedule because of the shortened development time achieved using the graphical system design approach.

With the CompactRIO platform and the LabVIEW Real-Time Module, the Optimation development team created the most efficient real-time system possible, which performed considerably more processing on the distributed controllers when compared to traditional PLCs.

The LabVIEW FPGA Compile Cloud Service helped Optimation greatly expedite system validation. Offloading the FPGA bitfile compilations preserved valuable resources on development computers and resulted in an up to 5.3 times improvement in compile times.

By using a complete top-to-bottom NI solution, Optimation’s development team aggressively executed the project, leading to a solution for NREL that was ahead of schedule and under budget.

More Info

• National Instruments
• National Renewable Energy Laboratory
• Optimation