Abstract
The topics introduced in this thesis are: the Finnish
load research
project, a simple form customer class load model,
analysis of the origins
of customers load distribution, a method for the
estimation of the
confidence interval of customer loads and Distribution
Load Estimation
(DLE) which utilises both the load models and
measurements from
distribution networks.
These developments bring new knowledge and understanding
of electricity
customer loads, their statistical behaviour and new
simple methods of how
the loads should be estimated in electric utility
applications. The
economic benefit is to decrease investment costs by
reducing the planning
margin when the loads are more reliably estimated in
electrc utilities. As
the Finnish electricity production, transmission and
distribution is moving
towards the deregulated electricity markets, this study
also contributes
to the development for this new situation.
The Finnish load research project started in 1983. The
project was
initially coordinated by the Association of Finnish
Electric Utilities and
40 utilities joined the project. Now there are over 1000
customer hourly
load recordings in a database.
A simple form customer class load model is introduced.
The model is
designed to be practical for most utility applications
and has been used by
the Finnish utilities for several years. There is now
available models for
46 different customer classes. The only variable of the
model is the
customers annual energy consumption. The model gives the
customers average
hourly load and standard deviation for a selected month,
day and hour.
The statistical distribution of customer loads is studied
and a model for
customer electric load variation is developed. The model
results in a
lognormal distribution as an extreme case. The model is
easy to simulate
and produces distributions similar to those observed in
load research data.
Analysis of the load variation model is an introduction
to the further
analysis of methods for confidence interval estimation.
Using the `simple form load model, a method for
estimating confidence
intervals (confidence limits) of customer hourly load is
developed. The two
methods selected for final analysis are based on normal
and lognormal
distribution estimated in a simplified manner. The
simplified lognormal
estimation method is a new method presented in this
thesis. The estimation
of several cumulated customer class loads is also
analysed.
Customer class load estimation which combines the
information from load
models and distribution network load measurements is
developed. This
method, called Distribution Load Estimation (DLE),
utilises information
already available in the utilitys databases and is thus
easy to apply. The
resulting load data is more reliable than the load models
alone. One
important result of DLE is the estimate of the customer
class share to the
distribution systems total load.
Original language  English 

Qualification  Doctor Degree 
Awarding Institution 

Supervisors/Advisors 

Award date  29 Nov 1996 
Place of Publication  Espoo 
Publisher  
Print ISBNs  9513849473 
Electronic ISBNs  9513852008 
Publication status  Published  1996 
MoE publication type  G4 Doctoral dissertation (monograph) 
Keywords
 electric power generation
 electric power distribution
 electric loads
 load research
 load estimation
 electricity
 distribution systems
 customers
 measurement
 models
 variations
 analyzing
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Seppälä, A. (1996). Load research and load estimation in electricity distribution: Dissertation. VTT Technical Research Centre of Finland. http://www.vtt.fi/inf/pdf/publications/1996/P289.pdf