High performance active filtering solutions for modern aircraft power network

Liu, Jun yi (2011) High performance active filtering solutions for modern aircraft power network. PhD thesis, University of Nottingham.

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In the past 2 decades the increasing intensive use of non-linear loads has resulted in a substantial reduction of power quality in electric power systems. Current harmonics produced by non-linear loads, such as power electronic converters and electrical drives cause a number of problems in power distribution networks. In more recent years this problem has affected also smaller distribution grids like for example in aircrafts, due to the so called "more electric aircraft" trend, consisting in the replacement of most of hydraulic/pneumatic actuators with electronically controlled electromechanical devices. Electrically powered actuation is becoming more attractive due to technology advances in bespoke equipment among which electrical motors, magnetic materials, electronic control circuits and power devices. Power electronics converters are required to control electrical power and are necessary for example for actuator motor drives and to convert variable frequency (360-800Hz) in the next generation of civil aircraft to a constant frequency supply bus for various loads or to a DC supply bus. Although the presence of electrically powered equipment is desirable for weight and fuel cost reduction, the increase of electrical systems on board, and above all the presence of power electronic subsystems, brings severe challenges to aircraft power system distribution interns of power quality.

The aim of this research project is to investigate Shunt Active Filter (SAF) solutions to improve the quality of power of on-board grids. In particular advanced control strategies will be studied in order to enhance the SAFs' operation in maintaining high power quality in these particular power networks. Anyway, only harmonics compensation will be addressed, as considered SAF are not intended to alleviate other power quality potential issues such as current unbalance between phases, reactive power compensation. This research project presents the specific application of a wide-band current control method based on Iterative Learning Control (ILC) for aircraft power networks, and introduces enhanced design strategies to increase compensation accuracy and improve the robustness of the SAF control system by using a P-type ILC controller. Due to the fact that a variable supply frequency (360Hz - 800Hz) is adopted in the power networks of newly released aircrafts, this research project presents a close investigation of the P-type ILC current controlled SAF system in such application (together with the standard fixed 400Hz supply), and hence identifies suitable modifications for the SAF system control to provide an effective and accurate current harmonic cancellation during the supply frequency variation.

Considering both simulation and experimental results, it can be concluded that the proposed SAF control proved to be very effective for accurate reduction of current harmonics on aircraft power grids with both fixed and variable supply frequency, using ordinary equipment and reasonable switching frequency and also ensuring good dynamics in transient conditions.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Zanchetta, P.
Keywords: Electric filters, Active, Airplanes, Electronic equipment
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800 Electronics
Faculties/Schools: UK Campuses > Faculty of Engineering > Department of Electrical and Electronic Engineering
Item ID: 29401
Depositing User: Airey, Ms Valerie
Date Deposited: 23 Jul 2015 10:04
Last Modified: 17 Sep 2016 00:03
URI: http://eprints.nottingham.ac.uk/id/eprint/29401

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