Noel N. Schulz

A Multi-Agent Solution to Distribution Systems Restoration

The goal to provide faster and faster restoration after a fault is pushing the technical envelope related to new algorithms. While many approaches use centralized strategies, the concept of multi-agent systems (MAS) is creating a new option related to distributed analyses for restoration. This paper provides details on a MAS that restores a power system after a fault. The development of agents and behaviors of the agents are described, including communication of agents. The MAS is tested on two test systems and facilitates both full and partial restoration, including load prioritization and shedding.

A revised branch current-based distribution system state estimation algorithm and meter placement impact

With the development of automation in distribution systems, distribution supervisory control and data acquisition (SCADA) and many automated meter reading (AMR) systems have been installed on distribution systems. Also distribution management system (DMS) have advanced and include more sophisticated analysis tools. The combination of these developments is providing a platform for development of distribution system state estimation (DSE). A branch-current-based three-phase state estimation algorithm for distribution systems has been developed and tested. This method chooses the magnitude and phase angle of the branch current as the state variables. Because of the limited number of real-time measurements in the distribution system, the state estimator can not acquire enough real-time measurements for convergence, so pseudo-measurements are necessary for distribution system state estimator. The load estimated at every node from the AMR systems is used as a pseudo-measurement for the state estimator. The algorithm has been tested on three IEEE radial test feeders. In addition to this new strategy for DSE, another issue is meter-placement. This topic includes the type of measurement as well as the location of the measurement. Our results show the impact of these two issues on accuracy. Several general meter rules based on this analysis are outlined.

Development of Three-Phase Unbalanced Power Flow Using PV and PQ Models for Distributed Generation and Study of the Impact of DG Models

With the increased installations of distributed generators (DGs) within power systems, load flow analysis of distribution systems needs special models and algorithms to handle multiple sources. In this paper, the development of an unbalanced three-phase load flow algorithm that can handle multiple sources is described. This software is capable of switching the DG mode of operation from constant voltage to constant power factor. The algorithm to achieve this in the presence of multiple DGs is proposed. Shipboard power systems (SPS) have other special characteristics apart from multiple sources, which make the load flow difficult to converge. The developed software is verified for a distribution system without DG using the Radial Distribution Analysis Package (RDAP). The developed software analyzes an IEEE test case and an icebreaker ship system. System studies for the IEEE 37-node feeder without the regulator show the effect of different models and varying DG penetration related to the increase in loading. System losses and voltage deviations are compared.

Synchrophasor-Based Real-Time Voltage Stability Index

This paper presents a new online voltage stability index (VSI) that predicts the power system steady-state voltage stability limit. Starting with deriving a method to predict three types of maximum transferable power (real power, reactive power, and apparent power) of a single-source power system, a new VSI based on the calculated load margins is devised. In order to apply the VSI to large power systems, a method is developed to simplify the large network behind a load bus into a single source and a single transmission line using time-synchronized phasor measurements and network parameters. The simplified system model, to which the devised VSI can be applied, preserves power flow and voltage information of the particular load bus under study. The proposed VSI combined with the network simplification method provides the voltage stability margin of each individual load bus in an informative format and identifies the load bus that is the most vulnerable to voltage collapse. Test results from applying the VSI on two test systems validate its applicability for online applications

Optimized Restoration of Unbalanced Distribution Systems

A novel formulation for service restoration algorithm for unbalanced three phase distribution systems is described. This problem is a constrained multiobjective optimization formulated as a mixed integer non-linear programming problem. A comparison of the solutions with and without switch pairs has been made. The formulation was first validated using already developed three-phase unbalanced power flow software. The three-phase unbalanced power flow equations were embedded in the formulation, and hence separate calculations were not needed. Simulation results are presented for modified IEEE 13-node and IEEE 37-node test cases

CIM extensions to electrical distribution and CIM XML for the IEEE radial test feeders

The electric power utility is an extremely large enterprise and has many computer systems and applications to complete both business and engineering functions. An efficient information exchanging and sharing infrastructure is key to the success of an electric utility. To facilitate the integration, a common data model is needed as a common language by which systems and applications can talk with each other. This research focuses on creating a common data model for the electrical distribution. It extends the CIM to electrical distribution for the data requirements by the distribution power flow and proposes modified models for distribution lines, distribution loads, and some specific distribution devices. It converts the IEEE radial test feeders to distribution CIM-based XML documents and provides an initial reference model for the electric distribution data in CIM XML format. These CIM XML documents have been tested and reviewed by industrial contacts. More tests are encouraged to check the interoperability of the proposed model and created CIM XML documents of the IEEE radial test feeders.

Knowldege-Based System for Distribution System Outage Locating Using Comprehensive Information

This paper presents a knowledge-based system (KBS) designed to locate distribution system outages using comprehensive data from customer trouble calls, a wireless automated meter reading (AMR) system, and distribution supervisory control and data acquisition (SCADA). The algorithm uses the on-demand read capability of a wireless AMR system, which allows the utility to communicate directly with the meter controllers. The algorithm of the developed KBS has two major parts: an outage escalation procedure and meter-polling procedure. The escalation procedure involves searching for the outage region according to the comprehensive outage information. The meter-polling procedure includes designing the meter-polling schema and confirming the outage locations based on the meter polling results. The algorithm was designed to handle both single outage and multiple outage situations. The expert system shell, G2, was used as the development tool.

Application of Genetic Algorithm for Reconfiguration of Shipboard Power System

Reconfiguration of the electrical network in a shipboard power system is a critical activity that is required to either restore service to a lost load or to meet some operational requirements of the ship. Reconfiguration refers to changing the topology of the power system in order to isolate system damage and/or optimize certain characteristics of the system related to power efficiency. When finding the optimal state, it is important to have a method that finds the desired state within a short amount of time, in order to allow fast response for the system. Since the reconfiguration problem is highly nonlinear over a domain of discrete variables, the genetic algorithm method is a good candidate. In this paper, a reconfiguration methodology, using a genetic algorithm, is presented that will reconfigure a given network, satisfying the operational requirements and priorities of loads. It also considers islanding to restore supply to critical loads after a fault is encountered. As a preliminary work, the proposed method has been applied to a simple 8-bus shipboard power system model and the concept will be extended to larger power systems.

Electric Power Engineering Education Resources 2005–2006 IEEE Power Engineering Society Committee Report. The Power Engineering Education Committee (PEEC) Task Force on Educational Resources

This report is based on a survey of power engineering education resources in the U.S. and Canada similar to 12 earlier such efforts. This survey is conducted to determine the electric power engineering education resources available in Accreditation Board of Engineering and Technology (ABET)-accredited engineering programs in the U.S. and Canada for the 2005-2006 academic year. The report is limited to colleges and universities that replied to a questionnaire on a voluntary basis. For the 125 colleges and universities (115 U.S., 10 Canadian) that submitted data on their power programs, the report contains a list of faculty active during the 2005-2006 academic year with academic participation and professional experience, each schools research area and funding levels, Ph.D. and M.S. student enrollment by type of support and by domestic versus international, and each schools power course offerings with enrollments and other data.

Using intelligent multi-agent systems for shipboard power systems reconfiguration

Many approaches have been taken on the reconfiguration of power systems, but most of these approaches use a centralized method. While these methods can be acceptable for terrestrial power system applications, doing reconfiguration on shipboard power systems has a different set of issues involved. For naval ships, that may experience damage during battle, a centralized reconfiguration method provides a limitation. Based on these constraints researchers are investigating decentralized control strategies that allow for reconfiguration using localized information. One newer technology that is showing promise in this area is intelligent multi-agent (IMA) systems. This paper discusses efforts underway at Mississippi State University to use IMA systems for reconfiguration of the power system. Agents are being implemented in multiple formats including Matlab and JADE to investigate the issues related to data sharing, communications and reconfiguration strategies