An Implementation of Parallel Buck Converters for Common Load Sharing in DC Microgrid

Abstract

The increase in demand for clean, safe, and environmentally friendly renewable energy sources faces several challenges such as system design and reliable operations. DC microgrid (MG) is a promising system due to higher efficiency and natural interface to renewable sources. In the hierarchical control of DC Microgrid, the V-I droop control is deployed usually in primary control level for common load sharing between converters. However, conventional droop control causes improper current sharing, voltage variations, and circulating current regulation due to the presence of droop and line resistance between converters. The aim of this paper is to presents the primary control level design of buck converters in current mode control according to the concepts of time constant and time delay, and secondary control design for parallel operations in distributed manners by combining methods, namely, low bandwidth communication (LBC), circulating current minimization techniques, and average voltage/current control. Moreover, different time delays are used for two converters to testify the effects of communication delays on current sharing and voltage restoration. The simulation is done for 2 × 2.5 KWdc parallel buck converters in PLECS (a Simulation software used for high speed simulation for power electronics) environment which shows excellent results in minimizing circulation currents, enhancing proportional current sharing, and restoring the grid voltage.

Data-driven demand-side energy management approaches based on the smart energy network

“…The smart energy management system integrates the internet of things (IoT), the internet, smart grid technologies, and microgrids. 20,21 Since it is also formulated as a network, we define the demand-side energy management system as a smart energy network throughout the rest of the paper.…”

Investigation of Adaptive Droop Control Applied to Low-Voltage DC Microgrid

“…The operation of different types of DG to meet the load needs a parallel operation but causes improper load sharing between converters and circulating current due to the abrupt variations in the source, sudden changes in load, and parametric differences due to various constraints [14]. Studies in the literature have discussed the most popular techniques of load sharing such as active current sharing [15][16][17] and droop control [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. The most familiar one is the master/slave technique, where, in the master/slave current method, a common bus is employed between DC converters for proper current sharing [15] and the generation of the required base voltage.…”

“…An advanced droop control method was proposed using an algorithm that improves power sharing and output voltage stability by changing the resistance in the classical droop equation. A new strategy for current control to minimize the circulating current with a combination of average voltage and the proportional current sharing controller was proposed, considering fixed droop resistance [27]. In [28], an adaptive droop control method was proposed to suppress circulating currents in a low-voltage DC microgrid.…”

Active Current Sharing of a Parallel DC-DC Converters System Using Bat Algorithm Optimized Two-DOF PID Control

“…The most common current-sharing technique is the openloop droop method, which independently regulates the output impedance or the voltage of the converter to realize uniform current distribution among the parallel-connected converters [7]. However, the droop control method may cause unbalanced current sharing and improper voltage variation due to the presence of droop and line resistance between converters [7]- [9]. Thus, some techniques have been developed to improve the conventional droop control such as primary droop control [10], improved droop control [11], [12], adaptive droop control [13], [14], generalized droop control [15], and closed-loop droop control [16].…”

“…A PDCC system with three parallel-connected bidirectional buck-boost converters and one external DSP controller was successfully developed. Compared with the existing PDCC systems, which can be only operated in buck or boost mode with single power transferring direction [5], [6], [9], [10], [21], the developed PDCC system provides dual power transferring directions and is available for both boost and buck modes. 2) Design of a new BA-optimized FB2PID control system: In this study, a new BA-optimized FB2PID control system that benefits from FB2PID control and online optimization was proposed.…”