OPTIMAL NUMBER AND PLACEMENT OF POWER QUALITY MONITORS FOR MONITORING VOLTAGE SAG IN POWER SYSTEM NETWORKS

Abstract

The occurrence of voltage sags often interrupt the operating process of modern equipment, especially in manufacturing and semiconductor plants. To avoid high production loss in industries, power quality monitoring is essential. Monitoring the whole power system will provide important data to a utility company. As most power system networks are large, allocating a Power Quality (PQ) monitor at every bus in the system is costly. Therefore, the optimal number of PQ monitors should be determined. In this thesis, an optimum number of PQ monitor locations is identified through a searching procedure developed based on the method of fault position combined with certain network characteristics such as the number of connecting lines and the size of the coverage area, or sag vulnerability area. The proposed searching procedure will be enhanced with the usage of monitor redundancy level. To allow redundancy in monitoring sags, a minimum of three recordings are required. This is to allow functioning of two recordings when a monitor fails. The monitor redundancy criterion is used to ensure that every fault in the power system can be observed and validated with sufficient redundancy to ensure the monitoring system is not affected when one of the monitors fails to function. The monitor searching procedure is developed by using the MATLAB software. The monitor searching procedure is simulated to three different IEEE standard test systems: IEEE 30, 118 and 300 bus systems. Simulation results demonstrate that it is possible to monitor the occurrence of a voltage sag in the entire power system with an optimum number of power quality monitors. The monitor searching procedure is then validated through the implementation of monitoring the voltage sag event in the Peninsular Malaysia’s utility network project. The number of monitors used under this project has been able to record sag events with optimum redundancy and the introduction of remote monitoring has enhanced the monitor searching procedure as the monitors used are able to upload data automatically to the database.