This paper presents an overview of the state of the art control strategies specifically designed to coordinate distributed energy storage (ES) systems in microgrids. Power networks are undergoing a transition from the traditional model of centralised generation towards a smart decentralised network of renewable sources and ES systems, organised into autonomous microgrids. ES systems can provide a range of services, particularly when distributed throughout the power network. The introduction of distributed ES represents a fundamental change for power networks, increasing the network control problem dimensionality and adding long time-scale dynamics associated with the storage systems’ state of charge levels. Managing microgrids with many small distributed ES systems requires new scalable control strategies that are robust to power network and communication network disturbances. This paper reviews the range of services distributed ES systems can provide, and the control challenges they introduce. The focus of this paper is a presentation of the latest decentralised, centralised and distributed multi-agent control strategies designed to coordinate distributed microgrid ES systems. Finally, multi-agent control with agents satisfying Wooldridge’s definition of intelligence is proposed as a promising direction for future research.

https://orbit.dtu.dk/files/190879836/C_Users_Thomas_Documents_UNSW_PhD_Research_Paper_Review_Control_for_Microgrids_with_Distributed_Energy_Storage_Systems_Draft_Final_160612_Review_MA_MG_ES.dvi.pdf

Control Strategies for Microgrids With Distributed Energy Storage Systems: An Overview

Microgrids are expected to become part of the next electric power system evolution, not only in rural and remote areas but also in urban communities. Since microgrids are expected to coexist with traditional power grids (such as district heating does with traditional heating systems), their planning process must be addressed to economic feasibility, as a long-term stability guarantee. Planning a microgrid is a complex process due to existing alternatives, goals, constraints and uncertainties. Usually planning goals conflict each other and, as a consequence, different optimization problems appear along the planning process. In this context, technical literature about optimization techniques applied to microgrid planning have been reviewed and the guidelines for innovative planning methodologies focused on economic feasibility can be defined. Finally, some trending techniques and new microgrid planning approaches are pointed out.

/pdf/computational-optimization-techniques-applied-to-microgrids-5dgs4pfdf5.pdf

Computational optimization techniques applied to microgrids planning: A review

Water management is paramount in countries with water scarcity. This also affects agriculture, as a large amount of water is dedicated to that use. The possible consequences of global warming lead to the consideration of creating water adaptation measures to ensure the availability of water for food production and consumption. Thus, studies aimed at saving water usage in the irrigation process have increased over the years. Typical commercial sensors for agriculture irrigation systems are very expensive, making it impossible for smaller farmers to implement this type of system. However, manufacturers are currently offering low-cost sensors that can be connected to nodes to implement affordable systems for irrigation management and agriculture monitoring. Due to the recent advances in IoT and WSN technologies that can be applied in the development of these systems, we present a survey aimed at summarizing the current state of the art regarding smart irrigation systems. We determine the parameters that are monitored in irrigation systems regarding water quantity and quality, soil characteristics and weather conditions. We provide an overview of the most utilized nodes and wireless technologies. Lastly, we will discuss the challenges and the best practices for the implementation of sensor-based irrigation systems.

https://www.mdpi.com/1424-8220/20/4/1042/pdf

IoT-Based Smart Irrigation Systems: An Overview on the Recent Trends on Sensors and IoT Systems for Irrigation in Precision Agriculture

Survey of multi-agent systems for microgrid control

In a traditional power grid, power generation is done at various potential locations and transmitted into power grid and then distributed to the customer premises The traditional grid incurs heavy investment, limited reliability, increased emissions of green house gases and increased transmission line losses It has made the utility to opt for connecting numerous renewable based micro sources near the customer premises, as per their requirement and providing intelligent control for the grid As a comprehensive solution, microgrids are suggested by the researchers which would provide reliable, quality and efficient supply to its customers The connection of microgrid in the existing distribution network makes the radial network more complicated It also causes the magnitude of fault current to change dynamically depending on the modes of operation (grid connected or islanded mode), type of distributed generator, status of distributed generators and number of distributed generators The conventional protection schemes are designed for radial power flow with centralized power generation, which makes the existing protection scheme to fail with the microgrid Hence, an attempt is made to relook into the basic concepts and significance of microgrid, issues faced by the microgrid in the context of protection and various protection strategies

A review on issues and approaches for microgrid protection

The application of Multi-Agent Systems (MAS) in electrical power systems are becoming popular due to their inherent benefits such as increased autonomy, reactivity, proactivity and social ability. This paper reviews current research on the application of multi-agent systems in microgrid schemes. The paper is mainly focused on recent developments of multi-agent systems in different aspects of microgrids such as control, market modeling, optimization and power restoration. The future directions of multi-agent systems in microgrid applications are also discussed briefly. Furthermore, this review is concluded by discussing the development of an enhanced multi-agent based distributed control framework for microgrids.

A review on multi-agent systems in microgrid applications

The following paper presents the concept of a layer jamming based soft glove for hand tremor suppression, its implementation, validation of the soft glove for hand tremor suppression and evaluation of the effect of layer jamming actuator placement. Wearable tremor suppression devices can avoid the side effects which occur due to available medical treatments, but contemporary methods are bulky and negatively affects the voluntary motions of the hand. Hence, a soft tremor suppression device can be developed to overcome the issues faced in contemporary wearable devices. A hand tremor suppression device using layer jamming was proposed in the study. In this study, experimentation for the material selection for layer jamming elements, evaluation of the layer jamming element placement and validation of the soft glove were conducted to characterize and evaluate the performance of the soft glove. Layer jamming material selection was done by measuring the deflection against an applied load. The performance of the soft glove was evaluated by measuring the suppression of a simulated tremor for the dorsal and palmar configurations. Performance evaluation shows a maximum tremor reduction of 78.32% in the palmar side element configuration in comparison to 38.23% in the dorsal side. Performance evaluation shows promising results in the suppression of hand tremors using the proposed soft glove and the results suggest that the palmar side element configuration can achieve higher tremor reduction comparatively.

A Novel Soft Glove for Hand Tremor Suppression: Evaluation of Layer Jamming Actuator Placement

Lawn maintenance is a tedious task that requires watering, mowing and fertilizing to be carried out at regular intervals to maintain a healthy lawn. Significant wastage and pollution occurs due to improper lawn maintenance practices. With many repetitive and routine tasks being replaced by robotic systems, lawn maintenance could also be achieved using a robotic system that would limit wastage and pollution, ensure a healthy lawn and reduce the work content of the lawn owner. This research presents a prototype robotic system developed to water a lawn efficiently by measuring soil moisture levels. The system comprises a tethered mobile platform and a watering system. The mobile platform is capable of measuring the soil moisture levels at a required depth and controls the water delivery based on pre-set moisture requirements. A novel Coverage path planning (CPP) algorithm was developed to account for the constraints posed by the tether and navigate to all accessible areas within a given lawn layout. The CPP algorithm uses a priori map consisting of environment data and prevalent static obstacles. This paper presents a fully autonomous system, which is able to water the lawn, traversing the path generated by CPP algorithm. The control system of the robot was developed using the Robot Operating System (ROS). The control system is designed in three layers. The higher level provides path planning and decision making, the mid-level provides communication with the hardware and carries out mandatory calculations and the lower level performs reading of sensor inputs and controlling of actuators. The control system was designed in a manner such that it can be remotely monitored and controlled. The developed platform was tested carrying out area coverage while watering a test area.

A mobile robot based watering system for smart lawn maintenance

This paper presents the design and simulation of a quantum tunneling composite (QTC) based tactile sensor array for use in pressure distribution measurement. QTC exhibits a rapid reduction in resistance with applied force making it suited for use in force sensing applications. Properties of QTC are exploited to design a tactile sensor array capable of measuring a dynamic pressure distribution over the sensor area. QTC acts a complete conductor after a certain stage reducing its effectiveness as a force sensor beyond that stage. QTC also takes considerable time to return to its original state after deformation due to force. These drawbacks found in QTC, limits its use to only that of a simple low cost switch. The proposed design for the tactile sensor array overcomes these drawbacks found in QTC material by incorporating a novel sensor array structure which enables an extended range of operation and allows rapid return to its unloaded state. This design allows for the use of QTC as a simple, cheap force sensor. The design can be further optimized to match the characteristics of the proposed sensor with the force range of a given application. A collection of such tactile elements is used to create a dynamic force sensing array. The design and simulation of the sensor array structure is described. This sensor array can be connected via a data acquisition system to a computer, which converts the data into a color contour map using LabView and MATLAB to measure and display the force distribution in realtime.

Quantum Tunneling Composite (QTC) based tactile sensor array for dynamic pressure distribution measurement

Conventional rigid robotic manipulators face difficulties when operating in confined areas. They also pose a safety risk when cohabiting a working environment with humans, animals or any other softer components. Soft and flexible robots provide a novel alternative solution in such places where the rigid system fails. Soft and flexible robotic manipulators are mostly inspired by biological counterparts such as elephant trunk and octopus arms. They have flexible limbs and redundant degrees of freedom where these characteristics enable special abilities such as variable bending, contraction, and stiffness. In this paper, the authors propose a soft vacuum bending actuator (VBA) that can be implemented as part of a soft flexible continuum robotic manipulator. The proposed actuator comprises a soft bendable silicone skeleton encompassed within a polyethylene (PE) film. When the air is removed from the cavity within the film, bending motion is obtained. In order to obtain multi-planar motion, two VBAs are connected in parallel to create a bimorph actuator. This paper presents the isotonic and isometric characterization of these devices. Experimental results show that a single VBA (132 mm length) was capable of lifting a maximum load of 204 g and achieving a 59 mm displacement (26◦bending angle) while lifting 90 g at 10 kPa (abs.) and that a 47 g bimorph actuator can generate a 169 g force in isometric testing. Finally, a simple prototype continuum arm design is implemented to validate the applicability of the actuators. The results validate the applicability of this novel vacuum-actuated soft bending actuator for use in continuum arm applications.

A.L. Kulasekera

Papers

A review on multi-agent systems in microgrid applications

A Novel Soft Glove for Hand Tremor Suppression: Evaluation of Layer Jamming Actuator Placement

A mobile robot based watering system for smart lawn maintenance

Quantum Tunneling Composite (QTC) based tactile sensor array for dynamic pressure distribution measurement

Design and Characterization of a Novel Vacuum Bending Actuator and a Bimorph: for Preliminary Use in a Continuum Robot Arm