Emma M. Stewart

The Local Team: Leveraging Distributed Resources to Improve Resilience

In recent years, extreme weather events have severely affected the performance of the electric grid. Very large-scale events (VLSE) with potentially catastrophic impacts on the grid pose more than an inconvenience in todays electricity-driven lifestyle, and the frequency and severity of such events may continue to increase as a consequence of global climate change. This article summarizes the state of the art in leveraging distributed resources to improve resilience of the electric grid. It also highlights the technical questions that need to be addressed through additional research and development if the value of distributed resources is to be maximized.

Addressing the challenges for integrating micro-synchrophasor data with operational system applications

This paper describes challenges for integrating high fidelity data with utility distribution operations. Two research projects are described microsynchrophasors (μPMU) and OpenPMU and explore the applications of data for electric power distribution systems.

Hardware-in-the-Loop co-simulation of distribution Grid for demand response

In modern power systems, co-simulation is proposed as an enabler for analyzing the interactions between disparate systems. This paper introduces the co-simulation platform Virtual Grid Integration Laboratory (VirGIL) including Hardware-in-the-Loop testing, and demonstrates its potential to assess demand response strategies. VirGIL is based on a modular architecture using the Functional Mock-up Interface industrial standard to integrate new simulators. VirGIL combines state-of-the-art simulators in power systems, communications, buildings, and control. In this work, VirGIL is extended with a Hardware-in-the-Loop component to control the ventilation system of a real 12-story building in Denmark. VirGIL capabilities are illustrated in three scenarios: load following, primary reserves and load following aggregation. Experimental results show that the system can track one minute changing signals and it can provide primary reserves for up-regulation. Furthermore, the potential of aggregating several ventilation systems is evaluated considering the impact at distribution grid level and the communications protocol effect.

Accuracy and validation of measured and modeled data for distributed PV interconnection and control

The distribution grid is changing to become an active resource with complex modeling needs. The new active distribution grid will, within the next ten years, contain a complex mix of load, generation, storage and automated resources all operating with different objectives on different time scales from each other and requiring detailed analysis. Electrical analysis tools that are used to perform capacity and stability studies have been used for transmission system planning for many years. In these tools, the distribution grid was considered a load and its details and physical components were not modeled. The increase in measured data sources can be utilized for better modeling, but also control of distributed energy resources (DER). The utilization of these sources and advanced modeling tools will require data management, and knowledgeable users. Each of these measurement and modeling devices have accuracy constraints, which will ultimately define their future ability to be planned and controlled. This paper discusses the importance of measured data accuracy for inverter control, interconnection and planning tools and proposes ranges of control accuracy needed to satisfy all concerns based on the present grid infrastructure.

Addressing the challenge of data interoperability for off-line analysis of distribution networks in the Smart Grid

As utilities move towards a more intelligent, autonomous distribution network with increased penetration of distributed generation there is a requirement for utilities and consultancies to analyze how these changes will affect network operation and performance under varying conditions. This requires a large amount of data and results to be moved on a frequent communications basis between applications from a number of different vendors, all of whom use their own proprietary data formats. This paper will discuss how these challenges are impacting off-line analysis of complex networks and how open standards can enable companies to efficiently share and exchange network models between incompatible applications.

A data-driven analysis of capacitor bank operation at a distribution feeder using micro-PMU data

In this paper, we conduct a data-driven experimental analysis on capacitor bank switching event at a distribution grid in Riverside, CA using data from two distribution level phasor measurement units, a.k.a, μPMUs. Of particular interest was to detect the capacitor bank switching events based on feeder-level and load-level μPMUs and thus eliminating the need to install separate sensors for the switched capacitor banks. In addition, the operational parameters of capacitor bank is investigated. Moreover, the dynamic effects of capacitor bank switching events is also considered through voltage and current synchrophasor data. This paper takes a first step in using μPMU data to conducting a detailed analysis of how different voltage-levels are affected by capacitor bank switching events in distribution systems.

Micro Synchrophasor-Based Intrusion Detection in Automated Distribution Systems: Toward Critical Infrastructure Security

Because electric power distribution systems are undergoing many technological changes, concerns are emerging about additional vulnerabilities that might arise. Resilient cyber-physical systems (CPSs) must leverage state measures and operational models that interlink their physical and cyber assets, to assess their global state. Here, the authors describe a viable process of abstraction to obtain this holistic state exploration tool by analyzing data from micro-phasor measurement units (μPMUs) and monitoring distribution supervisory control and data acquisition (DSCADA) traffic. To interpret the data, they use semantics that express the specific physical and operational constraints of the system in both cyber and physical realms.

Addressing misconceptions about the Common Information Model (CIM)

There are a number of highly significant misconceptions about what the CIM is, how it is used and what users should expect from products claiming CIM Compliance. This paper will try to address the reality of what the CIM is and how such significant misconceptions often reflect a misunderstanding about the CIM based on its most common implementations. The issue of CIM compliance will be considered from the perspective of profiling and interface definitions and why this makes the large, complex model, more manageable for those seeking to support a CIM interface.

Synchrophasor data analytics in distribution grids

The deployment of high-fidelity, high-resolution sensors in distribution systems will play a key role in enabling increased resiliency and reliability in the face of a changing generation landscape. In order to leverage the full potential of such a rich dataset, it is necessary to develop an analytics framework capable of both detecting and analyzing patterns within events of interest. This work details the foundation of such an infrastructure. Here, we present an algorithm for detecting events, in the form of edges in voltage magnitude time series data, and an approach for clustering sets of events to reveal unique features that distinguish different events from one another (e.g. capacitor bank switching from transformer tap changes). We test the proposed infrastructure on distribution synchrophasor data obtained from a utility in California over a one week period. Our results indicate that event detection and clustering of archived data reveals features unique to the operation of voltage regulation equipment. The chosen data set particularly highlights the value of the derivative of the localized voltage angle as a distinguishing feature.

Distribution Grid Reliability Versus Regulation Market Efficiency: An Analysis Based on Micro-PMU Data

There is a growing interest among power system operators to encourage load resources to offer frequency regulation. Prior studies have evaluated the system-wide benefits of such load resource participation. However, the potential adverse impact of wide scale load resource participation on distribution system performance, in the transient time frame, is often overlooked. Our goal is to address this open problem. We focus on a scenario where load resources offer regulation down service. To obtain realistic results, a distribution feeder in Riverside, CA, USA, is considered, where distribution-level phasor measurement units are used to collect high resolution voltage and current data. We start by developing a novel data-driven approach to analyze transient load behaviors. Subsequently, we model the aggregate load transient profile, in form of a three-phase surge current profile, that could be induced on a distribution feeder once a group of loads responds to a regulation down event. The impact of delay, e.g., due to sensing, communications, and load response, is considered. Distribution grid reliability is analyzed by taking into account the characteristics of the main feeder’s protection system as well as each lateral’s protection system. Both momentary and permanent reliability indexes are calculated. Case studies suggest that it is possible to jeopardize distribution grid reliability if several regulation down load resources are on the same feeder. Depending on various factors with respect to load resources, distribution feeder, and regulation market, there may or may not exist ways to break the trade-off between distribution grid reliability and regulation market efficiency. The construction and analysis of the reliability-efficiency curves would be needed for each feeder.