This study presents a method to interface an electromagnetic transient (EMT) simulator with a dynamic phasor (DP) simulation program. The hybrid DP–EMT simulator offers flexibility in deciding the harmonic contents to be preserved in the DP domain; additionally, it offers significant reduction in computing time of large networks compared with EMT simulation. The proposed interfacing method is based on a generic transmission line, which uses specialised numerical techniques to transfer discretised waveform samples between the two simulators. These numerical methods produce the required mapping between EMT simulation samples and their counterpart DPs. This study describes the mathematical foundations of the DP–EMT interface and demonstrates them using an illustrative example. Several large networks are then studied to assess the interface's accuracy and performance in reducing computing time.

This paper presents a quantitative analysis of the losses of the hybrid cascaded modular multilevel converter (HC-MMC). Regulation of full-bridge (FB) submodule-capacitor voltages in an HC-MMC requires dedicated strategies that affect the voltage harmonics generated by the converter's main power stage and hence its switching patterns and losses. This paper uses an electromagnetic transient simulator (PSCAD/EMTDC) to estimate the semiconductor losses using the switches' turn-on and turn-off characteristics. The paper examines the losses of a 45-MW HC-MMC for two recently introduced voltage-regulation methods based upon the modified sinusoidal pulse width modulation (PWM) and an existing method based upon the trapezoidal PWM. Losses of a conventional FB-MMC that offers dc-fault blocking capability are also investigated and compared with those of HC-MMC. The loss comparison results indicate that: first, the two voltage-regulation methods for HC-MMC based upon the modified sinusoidal PWM result in markedly lower semiconductor losses than the trapezoidal PWM method; second, compared with the original HC-MMC, a mixed submodule HC-MMC may lower the semiconductor losses at certain operating points with proper addition of mixed submodules; and finally, HC-MMC may have up to 9.0% lower semiconductor losses (relative) than the conventional FB-MMC.

An ultra-high gain DC-DC converter with single-switch structure is introduced in this paper. Full soft-witching is provided by simultaneous use of quasi-resonant performance of one resonant tank and leakage inductance of a three-winding coupled inductor (CI). Adopting the secondary and tertiary windings of the CI in separated voltage multiplier cells enables the converter to provide ultra-high voltage gain. The reverse recovery problem is resolved thanks to the quasi zero current switching performance of nearly all diodes, especially output diode because of the second resonant tank, so the total electromagnetic interference is significantly reduced. Continuous input current with low ripple expands the application of the proposed converter, especially in renewable energy applications. Steady-state performance and design considerations of the introduced converter are analyzed thoroughly and compared with recently introduced converters to establish its merits. Experimental results of a 200 W prototype are given to validate its analysis and performance.

This paper proposes a feed-back/feed-forward control strategy to attenuate the dc-link voltage variations in a reduced-capacitor battery energy storage system. It also identifies the impact of dc-link voltage variations on a battery energy storage system's response dynamics and power capabilities. It shows that addition of a feed-forward controller to the existing feed-back controller improves dc-link voltage regulation and consequently the response dynamics of the reduced-capacitor battery energy storage system. It formulates a power set-point change as a disturbance to the battery energy storage control system. The battery energy storage system is analyzed using an averaged-value modeling technique. Small-signal analysis is then used to tune feed-forward controller parameters. The performance of the proposed controller is evaluated via an electromagnetic transient software (PSCAD/EMTDC), and the findings are experimentally validated using a laboratory-sized test bench.