This paper describes a fast method for determining voltage changes due to line outages. Its extension to the identification of system islands as well as a formulation of a…
Abstract
This paper describes a fast method for determining voltage changes due to line outages. Its extension to the identification of system islands as well as a formulation of a voltage‐based contingency selection algorithm is explained. The performance of the method is evaluated using the 6‐bus Saskatchenan Power Corporation, IEEE 14‐bus and 23‐bus Nigerian Power Systems networks neglecting the effect of voltage controls.
This paper describes an algorithm which can be used to determine the optimal power flows of a network via the Dommel‐Tinney approach with or without the incorporation of security…
Abstract
This paper describes an algorithm which can be used to determine the optimal power flows of a network via the Dommel‐Tinney approach with or without the incorporation of security constraints; security constraints are properly handled via sensitivity analysis and least‐squares minimisation techniques. The algorithm can also determine the security enhancement of a network without taking the economics of operation into consideration. The refined second‐order loadflow method using rectangular coordinates is employed and the contingencies are determined by second‐order corrections on the base‐case; the computational aspects of this development are highlighted in the appropriate sections. The main emphasis of this paper is on numerical methods.
The superiority of the fast‐decoupled loadflow [FDLF] method is attributable to the underlying decoupling assumptions which, however, may not be valid for all modes of system…
Abstract
The superiority of the fast‐decoupled loadflow [FDLF] method is attributable to the underlying decoupling assumptions which, however, may not be valid for all modes of system operation. For example, during a restoration period following an emergency or in circumstances of unusual plant outages the assumptions of near nominal voltages and small phase angle differences may not be valid. Also for equivalencing methods, if large values of shunt admittance are contributed by the equivalent external networks, or if tap‐changing transformers are included, the FDLF method has shortcomings.
An alternative formulation of a linear method for transmission line overload alleviation is described based on the relationship between the line currents and voltage parameters…
Abstract
An alternative formulation of a linear method for transmission line overload alleviation is described based on the relationship between the line currents and voltage parameters defined in rectangular coordinates; the fast‐decoupled loadflow method is used for base calculations. Tests are carried out on the Saskatchewan Power Corporation 6‐bus network and the IEEE 14‐bus system.
Previously, a linear model was developed for investigating the optimisation of distribution system reliability for developing power systems. The economics of maintaining this…
Abstract
Previously, a linear model was developed for investigating the optimisation of distribution system reliability for developing power systems. The economics of maintaining this reliability level was established based on cost‐benefit and probability techniques. In this paper, a theoretical formulation is described to evaluate the time frame required to achieve this reliability level employing a nonlinear model.
In a companion paper, a theoretical framework of an algorithm was described which determines the optimal power flows of a network via the Dommel‐Tinney approach with or without…
Abstract
In a companion paper, a theoretical framework of an algorithm was described which determines the optimal power flows of a network via the Dommel‐Tinney approach with or without the incorporation of security constraints. This can be handled via sensitivity analysis and least‐squares minimization techniques. The aim of this paper is to report on the computational experiments of the method using the 5‐bus, 14‐ and 30‐bus networks.
K.L. Lo, W.P. Luan, M. Given, J.F. Macqueen, A.O. Ekwue and A.M. Chebbo
Voltage ranking attempts to rank busbar voltage deviations from their normally accepted security margins based on a set of performance indices (PI), without performing a full load…
Abstract
Voltage ranking attempts to rank busbar voltage deviations from their normally accepted security margins based on a set of performance indices (PI), without performing a full load flow. Existing methods suffer from either masking effects or long computation time. In this paper, an artificial neural network method is proposed for voltage ranking. Counterpropagation network (CPN) has been employed to overcome the problems listed above. A variety of input features are used with the aim of lowering the dimension of the proposed ANN to make it applicable for large power systems. The method is tested on two example systems, a five‐bus system and a 71‐bus system with very encouraging results.
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Artificial intelligence, including expert systems, fuzzy logic, neural networks and genetic algorithms, is increasingly being applied to the solution of a wide range of problems…
Abstract
Artificial intelligence, including expert systems, fuzzy logic, neural networks and genetic algorithms, is increasingly being applied to the solution of a wide range of problems in the monitoring and operation of electricity supply systems. Following the privatization of the Electricity Supply Industry in England and Wales in 1990, there is an overriding commercial incentive for the privatized electricity companies to operate the high voltage transmission networks as economically as possible without compromizing their reliability in a climate of substantial uncertainty as to the generator prices and availabilities that are bid into the pool from day to day and the energy trading contracts that have to be implemented. These circumstances often mean that the transmission and distribution networks must operate close to their defined security limits and still be capable of surviving severe disturbances. Hence artificial intelligence is being applied to the development of online real‐time monitoring systems to assist the electricity supply companies' control room engineers. This paper reviews this field and presents two case studies.
The purpose of this paper is to presents the current and prospective state of affairs when it comes to the information and communication technologies (ICTs) in condition…
Abstract
Purpose
The purpose of this paper is to presents the current and prospective state of affairs when it comes to the information and communication technologies (ICTs) in condition monitoring (CM) and maintenance, especially for the e-maintenance approach.
Design/methodology/approach
The author presents some of the standards for the domain of interest, such as the open system architecture condition-based maintenance. In addition, the e-maintenance approach is gone through as well as such ICTs as, for instance, the emergent web technologies, the service-oriented architecture (SOA), the web services and the Web 2.0 are analysed.
Findings
The findings highlight the need for a clearer understanding of the characteristics of different ICTs, such as Web 2.0 technologies, Cloud computing, agent technologies, etc., to be able to use them in an optimal manner for various purposes in the e-maintenance applications. In addition, the standardisation of the emergent ICTs different aspects is shown to be an important factor for the development of different phases of software as well as for its overall acceptance.
Research limitations/implications
The given work presents the current and emergent ICTs for the domain of interest and provides the discussion and various issues connected to these ICTs.
Practical implications
The author provides practical implications of the different ICTs mentioned in the paper, i.e. benefits and possibilities as well as risks when those technologies are implemented for CM and maintenance, especially for the e-maintenance.
Originality/value
The paper provides insight into various current and prospective ICTs for the domain of interest that provides important knowledge for different employees with the objective of a purchase, users of the system, such as technicians, maintenance engineers as well as developers of these systems. Consequently, the paper provides knowledge of different characteristics of the current and prospective technologies, which is important to take into account in order to be able not only to use them in an optimal manner, but also to understand possible constraints if they are used in the system and in applications in the domain.
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K.L. Lo, W.P. Luan, M. Given, M. Bradley and H.B. Wan
Automatic contingency selection aims to quickly predict the impact of a set of next contingencies on an electric power system without actually performing a full ac load flow…
Abstract
Automatic contingency selection aims to quickly predict the impact of a set of next contingencies on an electric power system without actually performing a full ac load flow. Artificial neural network methods have been employed to overcome the masking effects or slow execution associated with existing methods. However, the large number of input features for the ANN limits its applications to large power systems. In this paper, a novel feature selection method, named the Weak Nodes method, based on a heuristic approach is proposed for an ANN‐based automatic contingency selection for electric power system, especially for the voltage ranking problem. Pre‐contingency state variables of weak nodes in the power system are adopted as input features for the ANN. The method is tested on the 77 busbar NGC derived network by Counter‐propagation Method and it is proved that it reduces the input features for ANN dramatically without losing ranking accuracy.