Decentralized Load Sharing in a Low-Voltage Direct Current Microgrid With an Adaptive Droop Approach Based on a Superimposed Frequency

Abstract

Conventional droop methods for load sharing control in Low Voltage Direct Current (LVDC) microgrids suffer from poor power sharing and voltage regulation, especially in the case when operating many dc sources with long feeders. Hence, the communication based approaches are employed to improve the load sharing accuracy and voltage regulation. To avoid using such an infrastructure and the corresponding effects on the reliability and stability, an adaptive droop controller based on a superimposed frequency is proposed in this paper. Load sharing accuracy is improved by adapting the droop gains utilizing an introduced ac-power. The secondary controller locally estimates and compensates the voltage drop due to the droop controller. The proposed power sharing approach can properly control the load sharing and voltage regulation without utilizing any extra communication system. The effectiveness of the proposed control system is verified by simulations and experimental tests.

System-level lifetime-oriented power sharing control of paralleled DC/DC converters

“…In the proposed approach, the CL of converters is taken into account in which all the converters have the same lifetime consumption due to the load variation. In order to control the mentioned thermal stress of the converters, the conventional droop method [20] are employed where the droop gains are adjusted by the CL of the converters.…”

“…So far, power management and load sharing approaches have been presented employing voltage droop method [18], [19] and frequency droop control [20], [21], where the load sharing among paralleled converters has been performed proportional to the corresponding rated powers. Furthermore, reference [22] presents another droop approach taking into account the power loss of converters and hence improving the overall system efficiency.…”

Autonomous Power Management in LVDC Microgrids Based on a Superimposed Frequency Droop

“…he concept of ac/dc Microgrids (MGs) has been proposed in recent years to enhance the reliability, power quality and efficiency of the distribution power systems [1]- [6]. Future distribution systems will consist of many interconnected ac and dc MGs, which are dynamically decoupled from the each other [7], [8].…”

Enhanced Frequency Droop Method for load sharing in LVDC power systems

“…Hence some approaches have been presented to carry out the power management objectives without utilizing any physical communication system [4], [16]- [21].…”

“…SEDCPSA imposes ac ripples on the voltage and current of converters. To reduce the current ripples as well as improving the dynamic stability of the frequency droop method, the modified frequency droop approach is further presented in [21]. However, the voltage and current ripples still remain even though the modified approach is employed, which may affect the system efficiency and power quality.…”