The　unified　power　quality　conditioner　(UPQC)　is　known　as　an　effective　compensation　device　to　improve　PQ　for　sensitive　end-users.　This　paper　investigates　the　operation　and　control　of　a　single-phase　three-leg　UPQC　(TL-UPQC),　where　a　novel　space　vector　modulation　method　is　proposed　for　naturally　solving　the　coupling　problem　introduced　by　the　common　switching　leg.　The　modulation　method　is　similar　to　the　well-known　space　vector　modulation　widely　used　with　three-phase　voltage　source　converters,　which　thus　brings　extra　flexibility　to　the　TL-UPQC　system.　Two　optimized　modulation　modes　with　either　reduced　switching　loss　or　harmonic　distortion　are　derived,　evaluated,　and　discussed,　in　order　to　demonstrate　the　flexibility　brought　by　the　space　vector　modulated　TL-UPQC.　Simulations　and　experimental　results　are　presented　to　verify　the　feasibility　and　effectiveness　of　the　proposed　space　vector　modulation　approach　as　well　as　two　mentioned　modulation　modes.