TABLE OF CONTENTS This chapter describes the general distribution planning steps that may be taken in order to estimate the magnitude of the medium and low voltage distribution system loads to be supplied. It presents various load forecasting methods for estimating load development within the time period under review and within the specified geographic area under consideration. Such estimates and forecasts then allow the size of the necessary supply equipment and service overhead lines or cables to be calculated taking into account normal factors such as:
continuous current rating
line voltage regulation
fault rating
supply interference (motor starting, harmonic distortion, unbalance, etc.)
supply security
construction hazards and standards.
The overall efficiency of the distribution system is as important in load forecasting as energy consumption. Therefore load factor, maximum demand, diversity, losses and growth characteristics are particularly discussed. Modern distribution planning makes considerable use of computer modelling and equipment reliability statistics in order to assist with design optimization, and reference is made to such techniques.
This section defines some load definitions and describes the terminology used in distribution planning.
The demand of an installation or system is the load at the receiving terminals averaged over a specified interval of time .
The load may be expressed as active power (kW) or reactive power (kVAr). The period over which the demand is averaged is known as the demand interval and may be governed by the thermal constant of the equipment or...
