Decentralized Mode-Adaptive Guidance and Control for DC Microgrid

Abstract

This paper presents a decentralized, mode-adaptive (DMA) guidance law for a Hamiltonian-based controller of an N-source, dc microgrid. Droop control is commonly used for decentralized control of microgrids. Unfortunately, droop control lacks the ability to autonomously adapt to the addition or removal of a source without the augmentation of an outer loop controller. Centralized control methods provide solutions to these limitations, as well as providing the ability to globally optimize the system. To their detriment, centralized control methods are not scalable, and require system-wide information to be funneled through a central controller yielding a single point of failure. The DMA power apportionment scheme presented here aims to reduce the gap between droop control and centralized control by providing a method that can operate autonomously in the event of source and bus load fluctuations as well as reduce communication requirements of centralized control, and thus increase resiliency and scalability. After development of the DMA, its performance is compared to the centrally-controlled optimal exergy destruction (OXD) power apportionment strategy, as well as a Hamiltonianbased droop control strategy. Lastly, it is shown that for a sufficiently large number of converters supplying a microgrid, the presented decentralized, mode-adaptive strategy provides an efficient and practical alternative to both droop control and centralized control schemes.Index Terms-Dc power systems, decentralized control, distributed control, microgrids, power system control 0885-8977 (c)

Distributed Economic Power Dispatch and Bus Voltage Control for Droop-Controlled DC Microgrids

“…According to (5), all the state variables of each agent will converge to the same value, which depends on the initial values.…”

“…DC microgrids are gaining more and more attention due to the competitive advantages they provide over AC microgrids [2,3]. Firstly, DC microgrids can integrate the renewable energy sources (i.e., wind-power, photovoltaic), storage units (i.e., batteries, ultra-capacitors), and DC loads more efficiently, because the AC/DC and DC/AC conversion stages are avoided [4,5]. Secondly, there are no issues with frequency regulation and reactive power flow for the DC microgrids [6,7].…”

Optimal and Decentralized Control Strategies for Inverter-Based AC Microgrids

“…Conversely, it is known that the inverters are over-powering the bus load when the bus storage level is increasing. Similar to the decentralized mode adaptive guidance law of [21] for DC microgrids, the decentralized power apportionment guidance law for AC inverter microgrids exploits the state of the bus storage to indicate the power balance of the microgrid, and then adjusts accordingly.…”

Hybrid Fuzzy-Sliding Control Scheme for Bi-directional SEPIC Converter in Renewable Based DC Microgrid

“…This microgrid integrates different energy sources according to the energy availability of the area (solar energy, wind turbines, coal, liquefied petroleum gas, etc., although with a strong propensity for renewable resources, or renewable distributed energy resources -DER), and have a variable architecture according to the advantage of generating energy primarily from one or another energy source. This variable topology makes microgrid control and protection complex and an open-ended engineering research problem [4,5], particularly when considering power flow problems, load sharing, voltage regulation and mitigation of various kinds of power quality issues [6].A great energetic advantage of the microgrids is their greater electrical efficiency when feeding electronic type loads as variable speed drives and LED loads, because they do not need AC/DC and DC/AC converters when feeding them directly in direct current (DC) [7,8]. The DC power supply system has other advantages over the AC (alternating current) system, for example, it has higher reliability and lower cost (disappear problems of reactive power control, skin effect and frequency synchronisation).Among the main issues in the design and control of a DC microgrid are the selection of power converter topologies, voltage control and load sharing [9,10].…”

“…This microgrid integrates different energy sources according to the energy availability of the area (solar energy, wind turbines, coal, liquefied petroleum gas, etc., although with a strong propensity for renewable resources, or renewable distributed energy resources -DER), and have a variable architecture according to the advantage of generating energy primarily from one or another energy source. This variable topology makes microgrid control and protection complex and an open-ended engineering research problem [4,5], particularly when considering power flow problems, load sharing, voltage regulation and mitigation of various kinds of power quality issues [6].…”