This　article　proposes　an　approach　to　control　a　photovoltaic　cascaded　H-bridge　multilevel　inverter　with　failed　cells　and　changing　meteorological　conditions　for　large-scale　grid-connected　applications.　The　controller　development　is　based　on　an　analysis　of　the　interaction　between　the　inverter　common-mode　and　differential-mode　quantities,　which　is　done　in　the　time　domain,　supported　by　a　space　vector　representation　analysis.　The　proposed　approach　is　able　to　produce　balanced　three-phase　line-to-line　voltages　and　currents　even　if　there　is　a　failed　cell　or　if　the　fluctuating　meteorological　conditions　cause　uneven　power　distribution　among　the　bridges.　This　is　achieved　through　the　modification　of　the　pulsewidth　modulation　reference　phase　voltage　angles　combined　to　the　injection　of　a　dynamic　homopolar　component.　Such　an　approach　avoids　tripping　the　system　due　to　the　protective　functions　#25　and　#87　for　per　grid　applicable　codes　and　standards.　Numerical　simulations　and　laboratory　experiments　performed　on　a　seven-level　converter　with　different　abnormal　conditions　to　confirm　the　effectiveness　of　the　suggested　control　strategy.　©　1986-2012　IEEE.