Light Flicker and Harmonic Modelling of Electrical Lighting
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Compact Fluorescent Lamps (CFLs) have emerged as cost-competitive, energy efficient direct replacements of the conventional incandescent lamp. However, little regard has been given to their widescale adoption in terms of the electrical network and power quality. Discrepancies have emerged over the CFLs light flicker sensitivity to voltage fluctuations and concerns at the level of harmonics they generate. This thesis develops an objective measurement method for light flicker, overcoming the limitations of the existing IEC flickermeter standard and develops models using the Harmonic State-Space (HSS) framework and Harmonic Domain (HD) for harmonic studies.
The new light flickermeter proposed, measures light directly to quantify flicker, thereby removing the dependency of the incandescent lamp modelled in the current flickermeter standard, IEC 61000.4.15. The light flickermeter methodology resembles the same functional blocks of the IEC Flickermeter to produce equivalent perceptibility levels. This allows for the direct comparison of the two procedures. The Light flickermeter along side the IEC voltage flicker are implemented in the experimental system and fully calibrated to the newly proposed CCU2/CIGRE flickermeter test protocol. The sensitivity of CFLs to common voltage fluctuations are investigated and the light flickermeter is utilised in the design of a new LED fluorescent tube replacement lamp.
A linearised Harmonic State-Space (HSS) framework is developed for the modelling of non-linear devices. The methodology includes basic Kirchhoffs voltage and current laws to realise a control block diagram approach to a device’s operation. The HSS is centred around linear time periodic (LTP) systems and the use of harmonic transfer functions to model the switching behaviour (including Switching Instant Variation (SIV)) of converters. Importantly the models are suitable for both transient and steady state simulation. An example of a simplified CFL circuit is presented.
An automated sequential harmonic injection technique is developed for the experimental derivation of linearised harmonic admittance matrices of non-linear loads. This technique eliminates the traditional analytical based HD or HSS methods and creates a harmonic domain based model from the actual device. Models are presented for a number of consumer lamps. Detailed validation of these models are achieved under multi-frequency terminal conditions and through the illustration of self distortion by the system impedance.
This research paves the way in better understanding, management and coordination of flicker levels in electrical networks. The Light flickermeter apparatus provides a calibrated method for assessing light flicker sensitivity for both current and emerging technologies. The harmonic modelling methods are focussed towards lower powered devices and suited for studying their large scale use.