Effects of high penetration levels of residential photovoltaic generation

Photovoltaic (PV) generation technologies, often deemed a viable solution for reducing greenhouse gases and decreasing electricity demand, have become increasingly prevalent in their deployment. Particular progress in their implementation has been evidenced in residential areas characterized by rooftop-mounted PV arrays. Aside from the known advantages provided by residential PV generation, one noteworthy disadvantage confronting the electric utility is the degradation of power factor when grid-tied PV sources are extensively integrated into the electrical distribution system. In this paper, the effect of PV sources on power factor is studied using recorded field data from a residential community that is part of a large-scale smart grid demonstration project in Austin, Texas.Center for Electromechanic

Influence of parametric uncertainties and their interactions on small-signal stability : a case example of parallel-connected active loads in a DC microgrid

Classical stability analysis techniques based on nominal models do not consider the uncertainty of system parameters, their interactions, and nonlinearity, which are important characteristics of practical highly coupled microgrids. In this work, variance-based sensitivity analysis is used to identify parameter combinations that have a significant impact on the small-signal stability of a microgrid featuring two parallel active loads. The analysis indicates that the effectiveness of source-side damping is reduced when resonant frequencies of load input filters become matched. Further results using derivative-based sensitivity analysis reveal that source-side resistance can exhibit drastically different effects on the stability if load input filter resonant frequencies are matched with respect to the case when they are well separated. These behaviours are verified using time-domain switching models

Towards a Decision Support Tool for Assessing, Managing and Mitigating Seismic Risk of Electric Power Networks

Recent seismic event worldwide proved how fragile the electric power system can be to seismic events. Decision Support Systems (DSSs) could have a critical role in assessing the seismic risk of electric power networks and in enabling asset managers to test the effectiveness of alternative mitigation strategies and investments on resilience. This paper exemplifies the potentialities of CIPCast, a DSS recently created in the framework of the EU-funded project CIPRNet, to perform such tasks. CIPCast enables to perform risk assessment for Critical Infrastructures (CI) when subjected to different natural hazards, including earthquakes. An ad-hoc customization of CIPCast for the seismic risk analysis and management of electric power networks is featured in this paper. The international literature describes effective and sound efforts towards the creation of software platforms and frameworks for the assessment of seismic risk of electric power networks. None of them, unfortunately, achieved the goal of creating a user-friendly and ready available DDS to be used by asset managers, local authorities and civil protection departments. Towards that and building on the international literature, the paper describes metrics and methods to be integrated within CIPCast for assessing the earthquake-induced physical and functional impacts of the electric power network at component and system level. The paper describes also how CIPCast can inform the service restoration process

Interdependence between transportation system and power distribution system: a comprehensive review on models and applications

The rapidly increasing penetration of electric vehicles in modern metropolises has been witnessed during the past decade, inspired by financial subsidies as well as public awareness of climate change and environment protection. Integrating charging facilities, especially high-power chargers in fast charging stations, into power distribution systems remarkably alters the traditional load flow pattern, and thus imposes great challenges on the operation of distribution network in which controllable resources are rare. On the other hand, provided with appropriate incentives, the energy storage capability of electric vehicle offers a unique opportunity to facilitate the integration of distributed wind and solar power generation into power distribution system. The above trends call for thorough investigation and research on the interdependence between transportation system and power distribution system. This paper conducts a comprehensive survey on this line of research. The basic models of transportation system and power distribution system are introduced, especially the user equilibrium model, which describes the vehicular flow on each road segment and is not familiar to the readers in power system community. The modelling of interdependence across the two systems is highlighted. Taking into account such interdependence, applications ranging from long-term planning to short-term operation are reviewed with emphasis on comparing the description of traffic-power interdependence. Finally, an outlook of prospective directions and key technologies in future research is summarized.fi=vertaisarvioitu|en=peerReviewed

Consumer-data approach to assess the effect of residential grid-tied photovoltaic systems and electric vehicles on distribution transformers

The authors examine the impact of residential photovoltaic arrays and electric vehicles on distribution transformers by using 3-D surface and 2-D filled contour plots. These visualizations, somewhat unorthodox to power distribution analysis, elucidate the impact of hundreds of assets on distribution transformers on a single view. The visualizations are created with a smart grid computer model that accepts residential electrical recordings in one minute intervals. An analysis of simulation results shows that the electrical footprint experienced by a residential community and its distribution transformers stems from photovoltaic arrays rather than from electric vehicles. Additionally, the results indicate the existing distribution assets may be ready to support the proliferation of photovoltaic arrays and electric vehicles, a common concern across utilities in the United States.Center for Electromechanic

Open series fault comparison in ac & dc micro-grid architectures

This paper explores empirical observations of open series fault (arc fault) testing during current interruptions. Emphasis is on dc systems, but arc behavior is also compared to that of ac systems under >quasi-equivalent> circuit parameters. Specific parameters that are considered regarding arc behavior include gap voltage, current, dissipated power, voltage and current transient characteristics, reignition, bus disturbances, and contact position during dc arc collapse. Based on these results, comparisons between ac and dc systems seem to indicate that different arc-related challenges exist for both dc and ac architectures.Center for Electromechanic

Encrypted signal processing for privacy protection

In recent years, signal processing applications that deal with user-related data have aroused privacy concerns. For instance, face recognition and personalized recommendations rely on privacy-sensitive information that can be abused if the signal processing is executed on remote servers or in the cloud. In this tutorial article, we introduce the fusion of signal processing and cryptography as an emerging paradigm to protect the privacy of users. While service providers cannot access directly the content of the encrypted signals, the data can still be processed in encrypted form to perform the required signal processing task. The solutions for processing encrypted data are designed using cryptographic primitives like homomorphic cryptosystems and secure multiparty computation (MPC)

A dc arc model for series faults in low voltage microgrids

This paper presents a dc arc model to simplify the study of a critical issue in dc microgrids: series faults. The model is derived from a hyperbolic approximation of observed arc voltage and current patterns, which permit analyzing the arc in terms of its resistance, power, energy, and quenching condition. Recent faults staged by the authors on a dc microgrid yielded enough data to develop an arc model for three fault types: constant-gap speed, fixed-gap distance, and accelerated gap. The results in this paper compare experimental and simulation results for the three fault types. It is concluded that because the instantaneous voltage, current, power, and energy waveforms produced by the model agree well with experimental results, the model is suitable for transient simulations.Center for Electromechanic

Technical Cross-fertilization Between Terrestrial Microgrids and Ship Power Systems

Aspects of terrestrial microgrids and ship power systems are examined. The work exposes a variety of technical synergies from these two power systems to effectively advance their technologies. Understanding their overlap allows congruent efforts to target both systems; understanding their differences hinders conflict and redundancy in early-stage design. The paper concludes by highlighting how an understanding of both systems can reduce the investment in research resources.Center for Electromechanic