ISLANDS and AREAS of LIGHT – Infrastructure Development
Electricity – UHFAC Microgrid Papers - an Incunabulum of a real high frequency AC power distribution
https://repository.lib.ncsu.edu/bitstream/handle/1840.16/9877/etd.pdf?sequence=1
Summary of the Work:
"This dissertation presents a framework for the proposed novel Ultra-High-Frequency-AC (UHFAC) Microgrids.
The bus frequency and the power transmission frequency of the UHFAC Microgrids is pushed to 54 kHz.
The bus voltage waveform is quasi-square (trapezoidal) and the peak value is 400 V.
Compared to traditional Low-Frequency-AC (LFAC) Microgrids, the size and weight of the transformer and passive component in UHFAC Microgrids are significantly smaller; the distributed source interface and load interface converters are greatly simplified; the acoustic noise is eliminated; and wireless connection of power electronics interfaces is enabled.
Compare to traditional DC Microgrids, huge DC capacitors are eliminated since there is no DC bus to stabilize.
In addition, the proposed UHFAC Microgrids get rid of DC-arcing flash since the bus has current zero crossing points.
The circuit breaker therefore is much easier to develop than those in DC Microgrids.
Furthermore, short-circuit protection is possible to respond as fast as 9.26 µs,
which is the time interval between two nearest zero-crossing point.
Chapter 1 gives a review on the traditional LFAC Microgrids and DC Microgrids.
Existing 500 Hz HFAC Microgrids is also included for comparison.
Chapter 2 presents an in-depth analysis on the advantages of the proposed UHFAC Microgrids."
A novel distributed PV system with ultra-high-frequncy-AC bus for residential applications
https://ieeexplore.ieee.org/document/6953714
"In this paper, three existing distributed PV system configurations are reviewed and compared in depth. A novel ultra-high-frequency-AC (UHFAC) PV system for residential application is proposed. Compared with traditional DC parallel PV systems, this new approach eliminates the high voltage DC bus by replacing it with UHFAC bus, which avoids the DC arcing fault and enables ultra-fast short circuit protection as well. Resonance is utilized in this system to help UHFAC power transfer and realize soft-switching. Cable modeling is conducted to extract AC parameters, which helps validate the UHFAC power transmission (i.e., 100 kHz) in 30 to 40-feet-distance. Cable parameters also participate in the resonant intervals which demonstrates full utilization of system components. Simulation and experimental results are provided to verify the proposed approach."
"Renewable
energy resources, especially solar power, has drawn tremendous
interest in recent decades. Distributed and centralized PV systems
are two main architectures, while distributed system is favorable for
both industry and academic research. Because of radiation mismatch,
centralized PV system can expect a power loss of about 30% for
lacking of individual MPPT [1]. Power electronic technologies for
conditioning PV panel power fall into two big categories: panel
series solution and panel parallel solution."
[posted for educational purpose only]
Power Electronics Research Centre, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong
