| This thesis addresses the operation, control and application of high power active filter systems for harmonic mitigation. Proliferation of harmonic loads, on one hand, offers energy efficiency and increased industrial productivity. On the other hand, it causes resonances with utility/customer installed power factor correction capacitors, which result in propagation of harmonic voltages on distribution feeders. Supply voltage distortion affects equipment performance and may cause malfunction of sensitive loads, factory automation and industrial processes. Harmonic voltage distortion is therefore, a serious problem for both utilities and customers in distribution systems.; Both 'active' and 'passive' harmonic filtering approaches---do not offer an optimal solution for all harmonic producing loads. A methodology is developed for matching harmonic filtering solutions to harmonic producing loads, based on system issues. Merits and limitations of both 'pure' active filters and 'hybrid' active filters (combined system of active and passive filters), are identified and demonstrated through practical application and field installation results.; A general Synchronous Reference Frame (SRF) controller applicable for all active filter topologies is proposed. Control techniques and system implementation requirements for both 'pure' active and 'hybrid' active filters are developed. Shunt (or parallel) active filter approach is validated for a single harmonic producing adjustable speed drive load, by development of an industrial production unit to meet IEEE 519 recommended harmonic guidelines. To eliminate impact of background supply voltage distortion, 'harmonic isolation' function is demonstrated by 'hybrid' series active filter solution through field installation for a multiple and clustered harmonic load site. Active filter implementation and control for both hard-switched and soft-switched voltage source inverters are investigated. It is hoped that this thesis will enable cost-effective active filter solutions, based on system issues and requirements. |
