This　paper　presents　a　transformerless　static　synchronous　compensator　(STATCOM)　system　based　on　hybrid　multilevel　H-bridge　converter　with　delta　configuration.　This　hybrid　multilevel　STATCOM　is　characterized　by　per-phase　series　connection　of　a　high-voltage　H-bridge　converter　operating　at　fundamental　frequency　and　a　low-voltage　H-bridge　converter　operating　at　5　kHz　without　any　other　circuit　for　dc　voltage　control.　A　new　control　strategy　is　proposed　in　this　paper　with　focus　on　dc　voltage　regulation.　Clustered　balancing　control　is　realized　by　injecting　a　zero-sequence　current　to　the　delta-loop,　while　individual　voltage　control　is　achieved　by　adjusting　the　fundamental　content　of　ac　quasi-square-waveform　voltage　of　high-voltage　converter.　A　downscaled　experimental　prototype　rated　at　100　V　and　3　kVA　is　constructed　in　author＇s　laboratory.　Experimental　results　show　that　the　hybrid　multilevel　STATCOM　performs　satisfactory　not　only　improving　efficiency　and　waveform　quality,　but　also　compensating　reactive　power　and　negative-sequence　current　while　maintaining　dc　voltage　at　the　given　value.