A.R. Daniels

Modelling of operator heuristics in dispatch for security enhancement

This paper addresses the problem of dispatching active and reactive power on a large interconnected power system to maintain security. It models operator heuristics in the decision making process by means of fuzzy sets. Sensitivity analysis is then used to derive the necessary movements in control settings within a practical expert system that seeks a low cost, low number-of-controllers solution. Results are presented for a 20 machine, 100 bus reduced model of the UK national grid. Comparisons are shown with a linear programming approach and a conventional production rule based expert system implementation. The flexibility of the new approach is demonstrated whereby it can be used to model any number of operational criteria.

On-line stability constraint assessment for large complex power systems

Power systems around the world are increasingly subject to stability limits. Variation in operating conditions from scenarios used for off-line studies require the adoption of transmission limits. The result is the operation of less economic generation systems, leading to additional constraint costs. From an operational perspective, any on-line methods that could identify the generator contributions for a given stability problem and the generation changes required to operate closer to stability limits would be most valuable. This paper presents new developments, which have been carried out at the University of Bath, UK, in the areas of on-line stability constraint cost management for large complex power systems.

Real-time security assessment of electrical power systems

A new fast approach to electrical power network analysis is presented in this paper. A description of a real-time multimachine power system simulator, developed at the University of Bath (UK), is given, which has been used rather than the more conventional fast decoupled load flow. The operation of the algorithms that have been developed as part of this simulator are described, together with an explanation of how fuzzy set theory has been used for contingency screening and analysis, as well as the identification of power system transient and dynamic instability. Results are presented for these fuzzy algorithms and compared with traditional numerical methods for the IEEE 57 bus system and a reduced British National Grid network. Finally, conclusions are drawn in the light of these results, illustrating the benefits that can be achieved with respect to accuracy and computational speed.

The Nature Of The Power System Stability Surface

An increasing pressure on power system operators to operate their system closer to stability limits, together with continual advances in affordable computing power has motivated research into tools capable of automatically optimising ower system stability and economy. In .,!er to design any o timisation strategy it is essential to posses a thorough ungrstanding of the nature of the optimisation surface. In this light, this paper describes research, based upon an exhaustive analysis of the stability terrain of a small power system, which provides an essential insight into the system wide nature of power system stability. The paper demonstrates that even a small power system exhibits characteristics such as non-linearities and discontinuities, and includes many stability local minima, all of which are important considerations in the selection of suitable optimisation algorithms. The paper argues that, having demonstrated certain characteristics for a small power system, their are no logical reasons why the same characteristics should not be expected in larger and more complex systems, and thus strongly recommends that any algorithms for ower s stem stability optimisation should be accordingly gsignedl