eaNSF Network Simulation Facility

Introduction

EA Technology's Network Simulation Facility, eaNSF, was conceived as a tool to provide a basis for the economic and strategic evaluation of commercial and technical policies which depend intrinsically upon the engineering capacity and performance of the electricity distribution network.

The focus of eaNSF is to provide an environment where the economic aspects of different policies may be explored and where engineering constraints can be incorporated without necessarily having to develop or specify every detail that might be required for a conventional engineering analysis. While individual situations can be analysed by adapting conventional packages, it is much harder to investigate global policies, especially on the lower voltages where the network sizes are very large. Therefore the eaNSF has concentrated on voltages up to 33kV.
Incorporated in eaNSF is a facility to create generic networks to enable strategic level analysis to be performed without having to enter large amounts of company data.

Initially, the user loads a network by either creating a new network with Create Network, or by opening a previously created network with "Load Network Paths", or by loading a previously saved detailed network. Created networks give cable layout, consumer and supply positions but lack more detailed information such as switch positions. Therefore the basic network is then "populated" by the addition of switches, the sizing of transformers, etc.

After a network has been loaded, a scenario can be selected with Select Scenario. Scenarios guide the user through the steps required to analyse different polices. Within a scenario the user has a range of choices and parameters that can be set to more fully define a particular problem. For example, reliability calculations can be altered to, for example, take account of bad weather. The results are written to Excel spreadsheets which can be viewed by the program.

Electricity companies world-wide are facing the twin pressures of reducing costs and improving the quality of supply. With the improvement in the reliability of generation and transmission systems brought about by intensive technical development and capital investment, it is in many cases the distribution network which is the major cause of interruptions to the supply. With increased reliance on electricity, levels of performance which were formerly regarded as acceptable now cause significant disruption. The pressure for improved levels of performance, particularly in terms of reliability of supply, comes directly from the changing demands of the customers. This is emphasized both by increased public awareness of these issues and by requirements set by regulatory authorities which monitor the performance of the electricity companies on behalf of the public.

An area of key interest to the distribution companies is to investigate and compare different polices for improving the performance of the main distribution network (typically up to 30kV). Although faults on the low voltage distribution system may account for about the same number of customer faults, each fault on the main distribution network affects many more customers, and investment there is likely to yield much higher returns.

The EA Technology Network Simulation Facility (eaNSF) is a computer based decision support tool for comparing and evaluating a wide range of policy issues by accurately modelling networks and carrying out quantitative analysis. The most highly developed aspect is the capability to evaluate the regulatory customer performance indices (including the UK Office of Gas and Electricity regulation indices, Customer Interruptions and Customer Minutes Lost) in addition to other commonly used indices. eaNSF contains algorithms to carry out power system analysis and hence determine voltage drops, network losses and power flows. Sample half-hourly load demand curves for four classes of customers are supplied for typical days in the year from which annual figures may be estimated. As a result eaNSF includes a capability to calculate network losses and provide elementary economic assessment.

eaNSF is used to analyse strategic issues relating to customer performance and it is in use in a number of electricity utilities. This engineering tool is the most advanced decision support software for the development of strategies for investment on electricity distribution networks.

Network editor allows the user to enter networks manually and subsequently edit them and edit networks which have been imported previously into eaNSF. Each network would be made up of a number of modules which represent different components of the system.

All network plant data is stored in an excel spreadsheet, this spreadsheet is the source of all plant data used in the network studies. Typical information which would be stored in this spreadsheet would be cost, failure rates, maintenance times, response and repair times (including variations with weather). Once a network has been loaded into eaNSF, there are a number of scenarios which could be carried out, such as automation, load changes, plant change, network comparisons and reliability studies. Reliability - Calculation for each load point allows performance indices to be calculated, such as CI, CML's, SAIDI, SAIFI and ENS.

Fig 2) Network within Network Editor