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Eskom-ZESA interconnected power system modelling

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The power system frequency must be kept as close as possible to the nominal
value. This is due to the inherent design of electrical equipment to operate
efficiently at the nominal frequency. Frequency regulation in an interconnected
power system is the duty of all members of the interconnection. However, in the
Eskom-ZESA interconnected power system Eskom engineers ignore the
contribution of the ZESA system to primary frequency control. This is mainly
due to the prevalent assumption that the ZESA control area is small relative to
the Eskom control area and its contribution to primary frequency control of the
interconnected power system is negligible. This document presents a project
that examines the validity of this assumption via determination of the
contribution of the ZESA system to the interconnected power system’s primary
frequency control.
The interconnected power systems background was studied to understand the
theory behind the operation of two or more interconnected power systems.
System frequency disturbances deemed to be a good representation of the
Eskom-ZESA interconnected power system’s performance were selected and
analysed to validate the current assumption. The results show that there is a
significant support from ZESA during a system frequency disturbance. This
proves that the existing assumption is not valid anymore.
Furthermore; the generator model that mimics the Eskom-ZESA tie-line
governing behaviour was developed. Two different types of governor models
were employed; firstly the IEEEG1 governor was tuned to control generator
output to match the tie-line performance and then the TGOV5 governor model
was used. The IEEEG1 governor model is a simplified governor representation;
as a result, it is not easy to tune the parameters to match tie-line response.
However, the performance is acceptable and it can be used to represent the tieline
governor response. The TGOV5 governor model is very complex as
discussed in section 4.2. The model includes boiler dynamics, and this
improves performance such that it is possible to tune the parameters to follow
the tie-line performance as close as necessary. / GR2016
Date January 2016
CreatorsGumede, Nkosinomusa S
Source SetsSouth African National ETD Portal
Detected LanguageEnglish
FormatOnline resource (77 leaves), application/pdf, application/pdf

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