A State Equation Model of a Single-Phase Grid-Connected Inverter Using a Droop Control Scheme With Extra Phase Shift Control Action. - Henrique José Avelar; Wanderley Alves Parreira; João Batista Vieira; Luiz Carlos Gomes de Freitas; Ernane Antônio Alves Coelho (IEEE Trans. Ind. Electron., 2012)