Valentina Cecchi

A Survey of Communications and Networking Technologies for Energy Management in Buildings and Home Automation

With the exploding power consumption in private households and increasing environmental and regulatory restraints, the need to improve the overall efficiency of electrical networks has never been greater. That being said, the most efficient way to minimize the power consumption is by voluntary mitigation of home electric energy consumption, based on energy-awareness and automatic or manual reduction of standby power of idling home appliances. Deploying bi-directional smart meters and home energy management (HEM) agents that provision real-time usage monitoring and remote control, will enable HEM in “smart households.” Furthermore, the traditionally inelastic demand curve has began to change, and these emerging HEM technologies enable consumers (industrial to residential) to respond to the energy market behavior to reduce their consumption at peak prices, to supply reserves on a as-needed basis, and to reduce demand on the electric grid. Because the development of smart grid-related activities has resulted in an increased interest in demand response (DR) and demand side management (DSM) programs, this paper presents some popular DR and DSM initiatives that include planning, implementation and evaluation techniques for reducing energy consumption and peak electricity demand. The paper then focuses on reviewing and distinguishing the various state-of-the-art HEM control and networking technologies, and outlines directions for promoting the shift towards a society with low energy demand and low greenhouse gas emissions. The paper also surveys the existing software and hardware tools, platforms, and test beds for evaluating the performance of the information and communications technologies that are at the core of future smart grids. It is envisioned that this paper will inspire future research and design efforts in developing standardized and user-friendly smart energy monitoring systems that are suitable for wide scale deployment in homes.

Incorporating Temperature Variations Into Transmission-Line Models

This paper discusses a transmission-line modeling approach that incorporates available ambient temperature information. Several proposed line modeling techniques are studied and include distributed and lumped parameter models. In order to capture the nonuniformity of line parameters caused by temperature gradients, a model with multiple nonuniform segments is also proposed. An automated tool has been developed to obtain appropriate line model segmentation and parameter values of each segment, given a set of temperature measurements and their locations along the line.

Instrumentation and Measurement of a Power Distribution System Laboratory for Meter Placement and Network Reconfiguration Studies

At Drexel University, instrumentation and measurement of the reconfigurable distribution automation and control laboratory include hardware and software instruments which together form an automated measurement and control system. This system contains special features that were included to enable meter placement and network reconfiguration studies. This paper presents an outline of the measurement and control system for the general laboratory and then focuses on the capabilities purposely added for the meter placement and network reconfiguration studies.

System Impacts of Temperature-Dependent Transmission Line Models

Summary form only given. This paper discusses system-level impacts of temperature-dependent transmission line models based on given ambient temperature profiles. In order to capture nonuniformity of line parameters caused by ambient temperature gradients, a line model characterized by multiple nonuniform segments is used. An automated tool has been developed to obtain appropriate system models, given a set of temperature measurements and their locations along each system branch. Using these models, the impacts of temperature variations are investigated with respect to line terminal behavior (bus voltage) and maximum power transfer characteristics. Results for the IEEE 30-bus test system are presented.

A Distribution Power Flow Experiment for Outreach Education

This paper presents a distribution power flow experiment for use in outreach education. The work was adapted from an existing power flow experiment by Yang et al. to target non-engineers with diverse educational backgrounds. Critical educational outcomes were identified. An iterative design process was developed to build the experiment. Subsequently, new laboratory activities and interactive manuals were created. Assessment surveys were designed for evaluation purposes. Feedback results from 26 participants are presented.

Modeling Approach for Transmission Lines in the Presence of Non-Fundamental Frequencies

This paper presents a transmission-line modeling tool to obtain a desired level of accuracy at non-fundamental frequencies. Specifically, the approach compares finitely segmented models to the uniformly distributed model in order to determine the appropriate segmentation of the line model for a desired frequency range. The line model performance is characterized through waveform propagation, including attenuation and phase shift. The software-based modeling tool is validated through hardware tests of different segmentations.

Grid impacts and mitigation measures for increased PV penetration levels using advanced PV inverter regulation

As part of the Renewable Systems Interconnection (RSI), exploring the impact of high levels of PV penetration on standard utility system planning methodologies is critical. In this paper, in order to evaluate the potential impacts on representative distribution feeders for a south-eastern utility that is facing the interconnection of increasing levels of Photovoltaic (PV) generation; detailed steady-state and dynamic modeling and simulation of the integrated systems are performed. The study was conducted on two representative feeders: an almost exclusively residential feeder, and a predominantly rural feeder. Multiple PV penetration levels based on Spring loading were considered: 33.3% and 75% of total feeder loading, and 75% of total connected capacity as extreme case. Steady-state and dynamic analyses were performed. Procedures used to evaluate these impacts and results and observations are discussed. Moreover, possible impact mitigation strategies and evaluation of PV inverter controllers for mitigating the negative impacts are assessed.

Increasing penetration of Distributed Generation with meshed operation of distribution systems

Electric distribution systems are traditionally operated in a radial manner. In order to accommodate the increasing penetration levels of Distributed Generation (DG), meshed operation of distribution systems is investigated in this paper. Different limiting factors for increasing penetration levels of DGs are discussed; then, a methodology that determines maximum DG penetration level based on bus voltage and line current constraints is described. Alternative meshed operation of distribution systems, viewed as a more long-term systematic solution to increase maximum allowable DG penetration, can then be evaluated using the described metrics. Results for a 69 bus test case are presented for the radial system as well as for select meshed configurations. The obtained results verify the ability of meshed networks to accommodate proliferation of DGs.

Minimum-cost generation-shedding for dynamic Remedial Action Scheme

This paper describes an approach for determining generation-shedding for dynamic Remedial Action Scheme (RAS) based on minimum cost. A generation-shedding cost function is developed based on generator fuel cost, startup/shut down cost, and bid price. The proposed method updates RAS control actions online based on the system operating conditions and cost functions. The Single Machine Equivalent (SIME) method is used to compute stability margins for credible contingencies. The proposed method is applied to a modified IEEE 39-Bus system. Test results demonstrate effectiveness of the proposed minimum-cost generation-shedding method.

Effects of stiffness factor on bus voltage variations in the presence of intermittent distributed generation

Electrical distribution systems are experiencing increased penetration levels of distributed generation thanks to economic incentives and technology cost reductions. Analyzing the effects of distributed generation on planning and operation of distribution system is typically done based on steady-state simulations; output variability of renewable dispersed generation units implies the need for more dynamic evaluation of their effects on the system and for the introduction of mitigating measures. The authors previous work has shown the advantages of select meshed configuration of distribution systems for accommodating higher levels of distributed generation considering steady-state voltage and current limitations. In this paper, after introducing stiffness factor and its relation to Thevenin equivalent impedance, the effects of intermittent photovoltaic systems on bus voltages are investigated. The IEEE 34-node test feeder in its radial and in different meshed configurations is used as test case. Results of the study verify the superior performance of select meshed configuration for accommodating intermittent renewable resources in distribution systems.