Luminita Cristiana Totu

Control for large scale demand response of thermostatic loads

Demand response is an important Smart Grid concept that aims at facilitating the integration of volatile energy resources into the electricity grid. This paper considers a residential demand response scenario and specifically looks into the problem of managing a large number thermostat-based appliances with on/off operation. The objective is to reduce the consumption peak of a group of loads composed of both flexible and inflexible units. The power flexible units are the thermostat-based appliances. We discuss a centralized, model predictive approach and a distributed structure with a randomized dispatch strategy.

A micro-grid battery storage management

An increase in number of distributed generation (DG) units in power system allows the possibility of setting-up and operating micro-grids. In addition to a number of technical advantages, micro-grid operation can also reduce running costs by optimally scheduling the generation and/or storage systems under its administration. This paper presents an optimized scheduling of a micro-grid battery storage system that takes into account the next-day forecasted load and generation profiles and spot electricity prices. Simulation results show that the battery system can be scheduled close to optimal even with forecast errors. ICLOCS software has been used for the numerical implementation.

Demand Response of Thermostatic Loads by Optimized Switching-Fraction Broadcast

Abstract Demand response is an important Smart Grid concept that aims at facilitating the integration of volatile energy resources into the electricity grid. This paper considers the problem of managing large populations of thermostat-based devices with on/off operation. The objective is to enable demand response capabilities within the intrinsic flexibility of the population. A temperature distribution model based on Fokker-Planck partial differential equations is used to capture the behavior of the population. To ensure probability conservation and high accuracy of the numerical solution, Finite Volume Method is used to spatially discretize these equations. Next, a broadcast strategy with two switching-fraction signals is proposed for actuating the population. This is applied in an open-loop scenario for tracking a power reference by running an optimization with a multilinear objective.

Utilizing network QoS for dependability of adaptive smart grid control

A smart grid is a complex system consisting of a wide range of electric grid components, entities controlling power distribution, generation and consumption, and a communication network supporting data exchange. This paper focuses on the influence of imperfect network conditions on smart grid controllers, and how this can be counteracted by utilizing Quality of Service (QoS) information from the communication network. Such an interface between grid controller and network QoS is particularly relevant for smart grid scenarios that use third party communication network infrastructure, where modification of networking and lower layer protocols are impossible. This paper defines a middleware solution for adaptation of smart grid control, which uses network QoS information and interacts with the smart grid controller to increase dependability. In order to verify the methodology, an example scenario of a low voltage grid controller is simulated under imperfect network conditions.

Demand Response of a TCL Population Using Switching-Rate Actuation

This paper considers the problem of actively managing the power consumption of a large number of thermostatically controlled loads (TCLs), namely, a TCL population and a case study of household refrigerators. Control is performed using a new randomized actuation that consists of switching units ON and OFF at given rates, while at the same time respecting the nominal constraints on each individual unit. Both the free and the controlled behavior of individual TCLs can be aggregated, making it possible to handle a TCL population as if it were a single system. The aggregation method uses the distribution of the TCLs individual states across the population. The distribution approach has two main advantages. It scales excellently, since the computational requirements do not increase with the number of units, and it allows data from individual units to be used anonymously, which solves privacy concerns relevant for consumer adoption.

Modeling Populations of Thermostatic Loads with Switching Rate Actuation

We model thermostatic devices using a stochastic hybrid description, and introduce an external actuation mechanism that creates random switch events in the discrete dynamics. We then conjecture the form of the Fokker-Planck equation and successfully verify it numerically using Monte Carlo simulations. The actuation mechanism and subsequent modeling result are relevant for power system operation.

Control structures for Smart Grid balancing

This work addresses the problem of maintaining the balance between consumption and production in the electricity grid when volatile resources, such as wind and sun, account for a large percentage of the power generation. We present control structures for Smart Grid balancing services on three different levels: portfolio, larger scale individual power units, and aggregations of small power units. Our focus is on illustrating the connection between coordination and control algorithms.

Stochastic design of switching controller for quadrotor UAV under intermittent localization.

This paper presents a novel methodology for the design of motion controllers for UAVs of quad-rotor type. The developed controllers are of time switching type, where discrete modes are determined by the momentary availability of global positioning information. Relevant application scenarios are found, where the availability of GPS or generally GNSS is scarce, e.g. in case of indoor flight. For indoor flight dedicated indoor positioning technology may be applied, such as the ultra-sound/radio solution from [1]. Even with such technology available, due to reflection, interference and absorption, the required positioning service cannot be provided continuously without intermittency. A control model is presented, for which a general observer based controller framework is suggested. Feedback and observer gains are then allowed to switch according to the availability of positioning information. The mechanical states of the UAV are inherently un-observable in the absence of positioning information. Therefore the controller, in that case, will be unstable. However, by designing a set of feedback/observer gains to obtain stochastic stability under a given stochastic model for the switching process, an overall well functioning controller is obtained.

Identification of Thrust, Lift, and Drag for Deep-stall Flight Data of a Fixed-wing Unmanned Aircraft

In this paper, we consider a small unmanned aircraft and data collected during regular and deep-stall flight. We present an identification method for the thrust force generated by the propulsion system based on the in-flight measurements where we make use of the well-known linear and quadratic approximations of the lift and drag coefficients, respectively, for low angles of attack. This overcomes the lack of propeller thrust measurements and the obtained models are successfully evaluated against CFD simulation. The identified thrust model proves applicable beyond low angles of attack, thus enabling force estimation in the full flight envelope.

Easy 3D Mapping for Indoor Navigation of Micro UAVs

Indoor operation of micro Unmanned Aerial Vehicles (UAV or UAS) is significantly simplified with the capability for indoor localization as well as a sufficiently precise 3D map of the facility. Creation of 3D maps based on the available architectural information should on the one hand provide a map of sufficient precision and on the other limit complexity to a manageable level. This paper presents a box based approach for easy generation of 3D maps to serve as the basis for indoor navigation of UAS. The basic building block employed is a 3D axis parallel box (APB). Unions of APBs constitute maps, which are by definition closed to basic set operations such as; union, intersection, set difference etc. The restriction to APBs is made in accordance with the tradeoff between simplicity and expressiveness, where real time requirements emphasize simplicity. The mapping approach is presented along with different approaches of selecting via points ensuring sufficiently efficient path planning and at the same time ensuring scalability by keeping complexity low. A proposition for minimal via point assignment is ensuring at least feasibility of path planning is presented. Feasibility is not proved formally. Instead results from a randomized statistical proof are given. 3D Mapping, via point assignment and calibration are all implemented in a stand alone software application. The application program provides, through a graphical user interface, the possibility to map indoor environments based on existing 2D floor maps.