J.R. McDonald

An Integrated SOFC Plant Dynamic Model for Power Systems Simulation

The design process of a SOFC plant dynamic model for a power systems simulation (PSS) commercial software package has revealed the trade-off between the satisfaction of the network dynamic requirements and a safe and durable cell operation that the plant controller should implement. This paper describes the initial fuel cell stack and power conditioner modelling methodologies that have addressed such issues.

A multiagent architecture for protection engineering diagnostic assistance

Protection engineers use data from a range of monitoring devices to perform post-fault disturbance diagnosis. In the past, heterogeneous intelligent systems have been developed to interpret the data and provide information to engineers to assist with the disturbance diagnosis task. The majority of these systems remain standalone due to the problems associated with systems integration. This paper proposes the use of multiagent systems for providing a flexible and scalable alternative to existing integration approaches. A novel multiagent system (MAS) has been developed entitled protection engineering diagnostic agents (PEDAs) which integrates a legacy SCADA interpretation system with new systems for digital fault recorder (DFR) record interpretation and for enhancing fault record retrieval from remote DFRs. The use of MAS technology provides a flexible and scalable architecture open to the introduction of new data interpretation systems. The paper discusses the benefits of a multiagent approach and the design and implementation of PEDA.

Dynamics of distribution networks with distributed generation

This paper discusses the results of case studies which assess transient and small-signal stability of distributed generators connected to utility distribution networks. It also presents an investigation of the interaction between the controllers of individual generators. Case studies are based on different levels of generation penetration and a variety of operating conditions of both the networks and the generators. Transient stability and small-signal stability were assessed using commercially available power system simulation software. The interaction between the controllers is initially examined using eigenanalysis. A novel approach, i.e., individual channel analysis and design (ICAD), is then utilised to obtain an insight into the dynamics of the multivariable control problem.

Translating CIM XML power system data to a proprietary format for system simulation

The problem of exchanging data between two or more organizations in a format that is accessible and understandable by each is a universal problem. Furthermore, the problem of translating or accessing data in the correct format for applications using proprietary data formats is challenging. Legacy software applications may endure, for some time given, regulatory expenditure pressures on electricity system operators and these require data translators (importer/exporter) and access facilities. The basis of this paper is that the Electric Power Research Institute (EPRI) common information model (CIM) in eXtensible Markup Language (XML) represents the first stage in a revolution of data exchange and manipulation for power systems. This paper explores the problem of translating data in the CIM XML format to the required format for such legacy power system analysis applications. This paper discusses solutions to some of the challenges in data translation, and illustrates how these solutions can be implemented.

Architecture of a Network-in-the-Loop Environment for Characterizing AC Power-System Behavior

This paper describes the method by which a large hardware-in-the-loop environment has been realized for three-phase ac power systems. The environment allows an entire laboratory power-network topology (generators, loads, controls, protection devices, and switches) to be placed in the loop of a large power-network simulation. The system is realized by using a real-time power-network simulator, which interacts with the hardware via the indirect control of a large synchronous generator and by measuring currents flowing from its terminals. These measured currents are injected into the simulation via current sources to close the loop. This paper describes the system architecture and, most importantly, the calibration methodologies which have been developed to overcome measurement and loop latencies. In particular, a new ¿phase advance¿ calibration removes the requirement to add unwanted components into the simulated network to compensate for loop delay. The results of early commissioning experiments are demonstrated. The present system performance limits under transient conditions (approximately 0.25 Hz/s and 30 V/s to contain peak phase- and voltage-tracking errors within 5° and 1%) are defined mainly by the controllability of the synchronous generator.

The use of artificial neural networks for condition monitoring of electrical power transformers

Abstract Condition monitoring of electrical plant represents an area of great interest to both manufacturing and utility companies within the electricity supply industry. De-regulation and privatisation entail that utilities must operate their systems in an optimal fashion and one of the technologies which can facilitate this is condition monitoring. Condition monitoring has a number of important benefits: unexpected failures can be avoided through the possession of quality information relating to the on-line condition of the plant and the consequent ability to identify faults or problems while still in the incipient phases of development; maintenance programmes can be condition based rather than periodically based; the plant may be utilised more optimally through the use of information relating to the plants real-time condition and/or performance – for example, the plant may be driven temporarily beyond its stated capacity if it is known that this will not cause any short-term problems. This paper will cover the generic capabilities of artificial neural networks, in both estimation and classification mode, for condition monitoring applications, using examples based around work that the authors have carried out with respect to the monitoring of a power transformer.

Planning for distributed generation within distribution networks in restructured electricity markets

Recent IEEE publications have been of great interest to those who have been investigating the requirements for power system planning in restructured, unbundled and competitive electricity markets. In particular, the increased uncertainty regarding generator siting and timing are problems that will tend to increase as competition in generation increases. The authors have been investigating a generic planning framework to meet the requirements of distribution companies in the United Kingdom with particular regard to embedded generation. The generic framework has been developed from an extensive survey of planning methodologies, with reference to standard industry planning practices and in recognition of the set of issues regarding embedded generation that require to be addressed through evaluation.

Automating power system fault diagnosis through multi-agent system technology

Fault diagnosis within electrical power systems is a time consuming and complex task. SCADA systems, digital fault recorders, travelling wave fault locators and other monitoring devices are drawn upon to inform the engineers of incidents, problems and faults. Extensive research by the authors has led to the conclusion that there are two issues which must be overcome. Firstly, the data capture and analysis activity is unmanageable in terms of time. Secondly, the data volume leads to engineers being overloaded with data to interpret. This paper describes how multi-agent system technology, combined with intelligent systems, can be used to automate the fault diagnosis activity. Within the multi-agent system, knowledge-based and model-based reasoning are employed to automatically interpret SCADA system data and fault records. These techniques and the design of the multi-agent system architecture that integrates them are described. Consequently, the use of engineering assistant agents as a means of providing engineers with decision support, in terms of timely and summarised diagnostic information tailored to meet their personal requirements, is discussed.

Generator maintenance scheduling using a genetic algorithm

Abstract In this paper we consider the problem of generator maintenance scheduling (GMS) in power systems. A genetic algorithm with a fuzzy evaluation function is proposed in order to overcome some of the limitations of conventional modelling and solution methods. A test GMS problem is formulated with a reliability objective and flexible and crisp constraints. A rule base and fuzzy sets are formulated for the objective and the flexible constraint using experience of solutions to the problem, and used to define a fuzzy evaluation function. This is used in a genetic algorithm (GA) with an integer representation of the schedule to solve the test problem. The results obtained from the GA with the fuzzy evaluation function are compared with those obtained using crisp evaluation functions. The comparison shows that the GA with the fuzzy evaluation function is an effective and practical approach for finding good solutions for GMS with flexible constraints.

Propulsion Drive Models for Full Electric Marine Propulsion Systems

Integrated full electric propulsion systems are being introduced across both civil and military marine sectors. Standard power systems analysis packages cover electrical and electromagnetic components, but have limited models of mechanical subsystems and their controllers. Hence electromechanical system interactions between the prime movers, power network and driven loads are poorly understood. This paper reviews available models of the propulsion drive system components: the power converter, motor, propeller and ship. Due to the wide range of time-constants in the system, reduced order models of the power converter are required. A new model using state-averaged models of the inverter and a hybrid model of the rectifier is developed to give an effective solution combining accuracy with speed of simulation and an appropriate interface to the electrical network model. Simulation results for a typical ship manoeuvre are presented.