Evaluation of Feasible Interlinking Converters in a Bipolar Hybrid Microgrid

Abstract

A bipolar hybrid microgrid is a new topology which benefits from the advantages of both alternating current (AC) and direct current (DC) microgrids. Interlinking AC/DC converter is the key of this topology which has the following characteristics: being able to provide two equal pole voltages in DC side; complying with the standards of current quality at AC side; being able to control active and reactive power independently in AC side, and transmitting bidirectional power. In this paper, two categories of power converters including single-stage and two-stage converters are proposed for this topology. A new cost-effective control strategy is added to the control of general grid-connected converter for each interlinking converter, and the control of autonomous DC-link pole voltage for both candidates is achieved. Detailed simulations based on the designed control strategies are conducted to validate the function of control strategies under the operation conditions of different DC sides. The performances of two selected interlinking converters with balanced and unbalanced DC loads are analyzed. Suggested power quality of microgrid and total harmonic distortion (THD) analysis are demonstrated in grid-tied and islanded modes. Eventually, semiconductor power loss simulations based on a closed-loop thermal network simulation are conducted. Thereby, the mutual effects of power loss and initial junction temperature are investigated.

Power management and coordinated control strategy of flexible interconnected AC/DC hybrid microgrid with back‐to‐back converters

“…When the system is small, the line resistance only has a small value. Since k p1 > > R line1 and k p2 > > R line2 , the following proceeds from Equation (20).…”

“…In order to apply to bipolar hybrid microgrids, a two‐stage IC with VSC and voltage balancer is proposed in ref. [20]. In addition, the solid‐state transformer (SST)‐based multiport IC is proposed to improve the power density of the IC 21 .…”

Hybrid Four-wire Three-Level Inverter Equipped with Model Predictive Control for UPS Applications

“…where v e (i) is the voltage prediction error, which is defined in (10), ξ lim (i) presents the current constraint, which is shown in (11), and switching effort (SW ) with a weighting factor (ζ w ) can be expressed as given in (12).…”

“…Each phase of FWNPCTLI can produce three voltage level, i.e., 0, 0.5V dc , V dc . 10 switch converter has been recently introduced in [10]- [12] as suitable replacement for NPC in three wire applications which has advantages over both two-and three-level converters, simultaneously, plus it is applicable to a variety of power ranges. However, the switching pattern of 10-switch converter is not as simple as standard three-level converters such NPC, active NPC and T-type converter due to lack of medium vectors [13].…”

Adaptive hierarchical control strategy for AC/DC microgrid considering SOC of energy storage

“…Reference [2] proposed a reverse droop control technology to control voltage amplitude and frequency. In reference [3], an improved E index U/I droop control for energy storage was constructed.…”