DIGITAL SIMULATION OF PRACTICAL VOLTAGE SAGS, CRITICAL MANUFACTURING PROCESS COMPONENTS AND MITIGATION EQUIPMENT

Voltage sag has become an important concern for utility and customers in recent years. Modern load or equipment and electronic devices are very sensitive to voltage sag, which may cause system shutdown or malfunction. The disturbances can cause major losses in revenue and loss of product from work in process. The high cost associated with these disturbances drives the increasing investments in mitigation devices. The main objective of the paper is to develop a simulator tool that can predict the behavior o f typical industrial process with practical sag data. This tool will help engineers design a product before making a real prototype or assess the effectiveness of critical components. The simulation can also be used to determine size and cost of the mitigation equipment required. We have selected to model and simulate the most commonly affected equipment by voltage sags in industrial processes. They are ac contactor and induction motor. We have also modelled Dynamic Voltage Restorer (DVR) and Uninterruptible Power Supply (UPS), which is the commonly used mitigation device. In this project, the digital simulation studies have been carried out using PSCAD/EMTDC program. The critical equipment models are used in the digital simulation to determine the dynamics response during voltage sags as well as to predict the ride-through capability of the equipment. Then, both mitigation equipment model and sensitive load model are integrated together so that a complete system can be simulated. The simulation used voltage sag data from a power quality monitoring projects in Peninsular Malaysia under TNB Research Sdn. Bhd that records the voltage sags events at 52 sites. These sites consist of various transmission levels and distribution levels. This paper is organized in such following way: section 11 will provide the simulation circuit models, which include the sensitive equipment and mitigation equipment model. In section Ill, the simulation results for each of the circuit models are presented. Finally, the conclusion is drawn in Section IV.

DIGITAL SIMULATION OF PRACTICAL VOLTAGE SAGS, CRITICAL MANUFACTURING PROCESS COMPONENTS AND MITIGATION EQUIPMENT Keywords:

Power Quality , Voltage Sag , Sensitive Equipment , Mitigation Equipment , PSCAD