High voltage, direct current (HVDC) is key for long-distance bulk electric power transmission. Siemens developed a revolutionary new test concept for HVDC components and selected us to guide industry experts from Siemens AG and scientists from Friedrich-Alexander University Erlangen-Nuremberg using the NI platform to implement a proof of concept for that new test circuit at record speed.
Building on the success of the proof of concept, we now support its migration into a fully-grown software test application for the world-wide leading facility for HVDC tests, which is currently being built from the ground up in Nuremberg.
Siemens is market leader in providing innovative energy transmission solutions. One of the core technologies for long-distance bulk energy transmission is HVDC (High Voltage Direct Current). Testing HVDC system components poses major challenges due to system complexity, high energy density, high currents and voltages and diverse test requirements. Especially the extremely powerful, thyristor-based “HVDC Classic” technology demands power-intense tests which result in time-consuming procedures and inflexible test circuits with existing test systems.
To address these challenges, engineers at Siemens AG came up with a concept for a revolutionary “HVDC Classic” test circuit. This revolutionary test circuit is based on the “HVDC PLUS” technology, which is Siemens’ new Modular Multilevel Converter (MMC) concept for power transmission, allowing for precise reproduction of high-power electric patterns such as sine functions.
How we helped
During the first phase, our development team was tasked with proving the feasibility of this new test circuit based on a scaled-down model converter.
We worked together with the experts of Siemens and the Friedrich-Alexander-University and helped design a software architecture that is flexible enough to accommodate the proof-of-concept, yet robust enough to serve as the base for the fully-fledged test application.
The objective of the second phase of the project is to transfer the results of the feasibility study to a fully-grown test facility.
We continue to work very closely with our customer, providing fast and super flexible test circuits within a stable, robust and highly-available turn-key test suite.
The new test facility in Nuremberg will house three test fields with similar yet distinctive features and parameter sets. Serving all three variations from a single software application poses one of today’s challenges in migrating the proof of concept.
The modular software architecture not only addresses these challenges, but also helps also with team collaboration, as do best practices and improved development processes.
The graphic above shows the structure of the software. A Windows computer is running the HMI. A control model from MATLAB / Simulink is integrated into the RT LabVIEW software through the Model Interface Toolkit.
Time-critical control and protection algorithms are implemented in the FPGA, with high determinism and stability. As a single FPGA does neither provide sufficient computing capacity nor enough I/O, multiple FPGAs have to be synchronized.
The NI platform provides an ideal ecosystem for facing the above-mentioned challenges: Easy hardware and software integration helped us with setting up a proof of concept at record speed. Using the Model Interface Toolkit we could easily make use of MATLAB Simulink models within a LabVIEW Real-Time environment at high performance. The Simulink models are already used to simulate HVDC converter controllers in Siemens’ R&D team, and with the new test circuit control unit we can turn these models into a closed loop control for test converters with real-world I/O. Later on, controller adaptions or replacements can easily be integrated into the new control system.
NI Real-Time & FPGA
The new test circuit’s control approach is based on the performance of FPGAs in a PXI rack, connected to the power electronic modules through a proprietary Converter Interface consisting of fibre optic connectors. The modularity of this setup and the diversity of available off-the-shelf hardware within the NI ecosystem make it
easy to meet changing test requirements in future. Our expertise in the development of embedded systems based on NI hard- and software was instrumental in achieving a robust and scalable solution in comparably short time.
Team Development Processes
The success of our project so far is inherently coupled with the diversity of our team: We integrated into the project team and work hand in hand with industry experts from Siemens and scientists from Friedrich-Alexander- University Erlangen-Nuremberg. Our experience in software architecture and team-based software development
complements the domain-specific skills of the other project team members, and our cooperative way of working based on mutual trust and respect allows all parties to benefit from each other.
Due to the narrow time frame of the project, only a very basic specification of the LabVIEW software could be prepared.
Borrowing heavily from various project management and software development methods, the project plan, the software architecture and the software specifications itself were discussed, designed and finalized – all in a very detailed way – step by step throughout the project. Requirements still have to be deducted from technical realities as we go, adding to the already challenging software development task.
In order to overcome or at least alleviate these obstacles, best-practice approaches are applied wherever possible to maximize code quality as well as developer experience while cutting down on development time.
Methods and tools include style guides and templates for source code and documentation, adoption of the DQMH framework for a common software structure, management of requirements and general documentation with Bookmark Manager, automated generation of documentation directly from source code, issue tracking, automated code testing with VI Analyzer and unit tests, formal and informal code reviews, source code management, automated build tools, or outsourcing FPGA compilation of the massive FPGA source code to a dedicated high-performance compile server.