PhD Research Project: Advanced control of distributed generation units to develop self-protected mi

Renewable energy sources and energy storage systems, which are integrated with the grid via suitable power electronic devices (converters), along with local loads form the microgrid architecture, which is the core module of the future power network. Depending on the type of the local grid, microgrids are divided into two main categories, ac and dc microgrids. The operation and control of distributed generation (DG) units in both ac and dc microgrids is crucial to maintain the stable and reliable operation of the entire system.

However, unpredicted scenarios such as faults, short circuits, sudden islanding, unrealistic power supply or demand, can significantly disturb the microgrid operation and force distributed generation units to operate outside their limits, which can consequently lead to a disconnection or damage of the converter device. In these cases, either protection circuits are triggered or the power converters of DG units are required to switch between different control algorithms to protect the entire system. Additional monitoring is usually needed and the entire system can be led to instability due to the lack of a rigorous stability proof.

This project will focus on the design of advanced control methods for converters of DG units in both ac and dc microgrid applications, which will have the same structure under both normal and abnormal conditions. The developed techniques will be based on a strong mathematical background and are required to guarantee a stable and safe operation under several adverse conditions (e.g. grid faults, unrealistic power demands, measurement errors, etc.), leading to the design of self-protected microgrids, which will enhance the resilience of the power network. Hardware-in-the-loop and experimental implementation of the developed methods are essential to verify the theoretical development.

Funding Notes

Prospective applicants should have a good first degree (I or II.i) and/or Masters degree in a mathematical or engineering-related subject. A background in nonlinear control/systems theory, power systems and/or electrical engineering and knowledge of DPS programming is desirable. Competence in Matlab/Simulink is essential.

References

Further Reading

M. Karimi-Ghartemani, “Universal integrated synchronization and control for single-phase dc/ac converters,” IEEE Trans. Power Electron., vol. 30, no. 3, pp. 1544–1557, Mar. 2015.
N. Bottrell and T. C. Green, “Comparison of Current-Limiting Strategies During Fault Ride-Through of Inverters to Prevent Latch-Up and Wind-Up,” IEEE Trans. Power Electron., vol. 29, no. 7, pp. 3786–3797, 2014.
A. D. Paquette and D. M. Divan, “Virtual Impedance Current Limiting for Inverters in Microgrids With Synchronous Generators,” IEEE Trans. Ind. Appl., vol. 51, no. 2, pp. 1630–1638, 2015.
J. W. Simpson-Porco, F. Dörfler, and F. Bullo, “Synchronization and power sharing for droop-controlled inverters in islanded microgrids,” Automatica, vol. 49, no. 9, pp. 2603–2611, 2013.
G. Konstantopoulos, Q.-C. Zhong, and W.-L. Ming, “PLL-less Nonlinear Current-Limiting Controller for Single-Phase Grid-Tied Inverters: Design, Stability Analysis and Operation Under Grid Faults,” IEEE Trans. on Industrial Electronics, 2016, to appear.