Distributed Passivity-Based Control of DC Microgrids

In this paper, we propose a new distributed passivity-based control strategy for Direct Current (DC) microgrids. The considered DC microgrid includes Distributed Generation Units (DGUs) sharing power through resistive-inductive distribution lines. Each DGU is composed of a generic DC energy source that supplies an unknown load through a DC-DC buck converter. The proposed control scheme exploits a communication network, the topology of which can differ from the topology of the physical electrical network, in order to achieve proportional (fair) current sharing using a consensus-like algorithm. Moreover, the proposed distributed control scheme regulates the average value of the network voltages towards the corresponding desired reference, independently of the initial condition of the controlled microgrid. Convergence to a desired steady state is proven and satisfactorily assessed in simulations

Distributed secondary control based on dynamic diffusion algorithm for current sharing and average voltage regulation in DC microgrids

This paper introduces a distributed secondary control scheme for achieving current sharing and average voltage regulation objectives in a DC microgrid. The proposed scheme employs a dynamic diffusion algorithm (DDA) instead of the consensus algorithm to enable distributed communication among converters. To help understand DDA, the relation of DDA and other diffusion algorithms is discussed in detail and its superiority is shown by comparison with diffusion and consensus algorithms. Furthermore, considering the discrete nature and different sampling time of the digital controller and communication network, a z-domain model of the entire DC microgrid is established. The influence of communication and secondary control parameters on the system stability is investigated. Based on the established model, the tolerable communication rates are obtained. Real-time simulations conducted on the OPAL-RT platform validate the effectiveness of the proposed scheme, showcasing its advantages in terms of convergence speed and stability

Stability analysis and nonlinear current-limiting control design for DC micro-grids with CPLs

In this study, a DC micro‐grid consisting of multiple paralleled energy resources interfaced by both bidirectional AC/DC and DC/DC boost converters and loaded by a constant power load (CPL) is investigated. By considering the generic dq transformation of the AC/DC converters' dynamics and the accurate nonlinear model of the DC/DC converters, two novel control schemes are presented for each converter‐interfaced unit to guarantee load voltage regulation, power sharing and closed‐loop system stability. This novel framework incorporates the widely adopted droop control and using input‐to‐state stability theory, it is proven that each converter guarantees a desired current limitation without the need for cascaded control and saturation blocks. Sufficient conditions to ensure closed‐loop system stability are analytically obtained and tested for different operation scenarios. The system stability is further analysed from a graphical perspective, providing valuable insights of the CPL's influence onto the system performance and stability. The proposed control performance and the theoretical analysis are first validated by simulating a three‐phase AC/DC converter in parallel with a bidirectional DC/DC boost converter feeding a CPL in comparison with the cascaded PI control technique. Finally, experimental results are also provided to demonstrate the effectiveness of the proposed control approach on a real testbed

Distributed passivity-based control of DC microgrids

In this paper, we propose a new distributed passivity-based control strategy for Direct Current (DC) microgrids. The considered DC microgrid includes Distributed Generation Units (DGUs) sharing power through resistive-inductive distribution lines. Each DGU is composed of a generic DC energy source that supplies an unknown load through a DC-DC buck converter. The proposed control scheme exploits a communication network, the topology of which can differ from the topology of the physical electrical network, in order to achieve proportional (fair) current sharing using a consensus-like algorithm. Moreover, the proposed distributed control scheme regulates the average value of the network voltages towards the corresponding desired reference, independently of the initial condition of the controlled microgrid. Convergence to a desired steady state is proven and satisfactorily assessed in simulations