ABSTRACT

HIDAYAT MOEIN. A Study on the South Sulawesi Power Transmission System Load Shedding (supervised by H. Nadjamuddin Harun and Indra Jaya).

The reliability of an electrical power system depends on its ability to minimize the effect of disturbance. The general method to minimize the effect of disturbance is by isolating it to avoid the spread of the effect that may cause the system to collapse.

There are several kinds of electrical power system disturbance. One of the most frequent disturbances that has an enormous impact on the system stability is related to the equilibrium factor between the load and the source at the power-generating unit. The disturbance is indicated by the system frequency fluctuation. If the load (in MW) is greater than the available power (in MW) generated by the source, then the system frequency will decrease, and vice versa. The reference frequency at equilibrium is 50 Hz.

A disturbance at the power-generating unit may cause a rapidly decreasing system frequency. To prevent a power system blackout, the disturbance should be anticipated by load shedding. There are 3 (three) stages of the load shedding controlled by an under-frequency relay (UFR) system, namely UFR-1 at 48.9 Hertz, UFR-2 at 48.5 Hertz and UFR-3 at 48.3 Hertz. 

In this study, the case of South Sulawesi power system is considered. The fluctuation of daily maximum and minimum load configuration is monitored in a week then the load flow at the transmission system is analyzed using the polar coordinate Newton-Raphson method, while the load shedding method …………….. (sorry, ndak mengerti saya).

It is concluded from the study that the implementation of the load shedding method with UFR-staging has improved the ability of the South Sulawesi power transmission system to minimize the effect of disturbance at the power-generating unit. It is also known that the stability of the power system during the day is worse than the stability during the night due to the large load variation (load-factor), even though the composition of the power sources has been set at its economical level.