A modular multilevel converter comprising: a first upper arm comprising a first active power link module, wherein the first active power link module is configured to selectively connect and disconnect a first ultracapacitor to the first upper arm to facilitate: producing a first portion of a first alternating current electrical power at a base frequency; and injecting a first even-order current harmonic of the base frequency in the first upper arm; a first lower arm comprising a second active power link module, wherein the second active power link module is configured to selectively connect and disconnect a second ultracapacitor to the first lower arm to facilitate: producing a second portion of the first alternating current, wherein the first portion of the first alternating current and the second portion of the alternating current are combined to facilitate outputting the first alternating current electrical power at a first alternating current terminal; and injecting the first even-order current harmonic in the first lower arm, wherein magnitude of the first even-order current harmonic is zero at the first alternating current terminal as a result of harmonics cancellation; wherein the first even-order current harmonic is configured to reduce root-mean- square current flowing in the first ultracapacitor and root-mean square of current flowing in the second ultracapacitor when the modular multilevel converter is in operation; characterized in that the base frequency is 60 Hz and the first even harmonic is 120 Hz; the first portion of the first alternating current comprises a first direct current component and a first 60 Hz component; the first even-order current harmonic comprises a first 120 Hz component; and current conducted by the first ultracapacitor comprises a second 60 Hz component, a second 120 Hz component, and a 180 Hz component, wherein the first even-order current harmonic is further configured to increase the magnitude of the ultracapacitor current at 180 Hz, while the reduction in magnitude of the ultracapacitor current at 60 Hz and at 120 Hz is greater than the increase in magnitude of the ultracapacitor current at 180 Hz, thereby reducing the root-mean square current of the ultracapacitor. a first upper arm comprising a first active power link module, wherein the first active power link module is configured to selectively connect and disconnect a first ultracapacitor to the first upper arm to facilitate: producing a first portion of a first alternating current electrical power at a base frequency; and injecting a first even-order current harmonic of the base frequency in the first upper arm; producing a first portion of a first alternating current electrical power at a base frequency; and injecting a first even-order current harmonic of the base frequency in the first upper arm; a first lower arm comprising a second active power link module, wherein the second active power link module is configured to selectively connect and disconnect a second ultracapacitor to the first lower arm to facilitate: producing a second portion of the first alternating current, wherein the first portion of the first alternating current and the second portion of the alternating current are combined to facilitate outputting the first alternating current electrical power at a first alternating current terminal; and injecting the first even-order current harmonic in the first lower arm, wherein magnitude of the first even-order current harmonic is zero at the first alternating current terminal as a result of harmonics cancellation; wherein the first even-order current harmonic is configured to reduce root-mean- square current flowing in the first ultracapacitor and root-mean square of current flowing in the second ultracapacitor when the modular multilevel converter is in operation; producing a second portion of the first alternating current, wherein the first portion of the first alternating current and the second portion of the alternating current are combined to facilitate outputting the first alternating current electrical power at a first alternating current terminal; and injecting the first even-order current harmonic in the first lower arm, wherein magnitude of the first even-order current harmonic is zero at the first alternating current terminal as a result of harmonics cancellation; wherein the first even-order current harmonic is configured to reduce root-mean- square current flowing in the first ultracapacitor and root-mean square of current flowing in the second ultracapacitor when the modular multilevel converter is in operation; characterized in that the base frequency is 60 Hz and the first even harmonic is 120 Hz; the first portion of the first alternating current comprises a first direct current component and a first 60 Hz component; the first even-order current harmonic comprises a first 120 Hz component; and current conducted by the first ultracapacitor comprises a second 60 Hz component, a second 120 Hz component, and a 180 Hz component, the first portion of the first alternating current comprises a first direct current component and a first 60 Hz component; the first even-order current harmonic comprises a first 120 Hz component; and current conducted by the first ultracapacitor comprises a second 60 Hz component, a second 120 Hz component, and a 180 Hz component,