Voltage Collapse: Real Time and Preventive Analysis in the Portuguese Transmission System

The objective of this paper is to describe a process which was developed in the Portuguese TSO (REN - Rede Electrica Nacional, SA) whose main purpose is to identify voltage collapse situations without the need for the specific EMS module. The process is based on the power flow module of PSS/E software from Siemens Power Transmission Distribution, Inc., running automatically through an application developed in Python, which performs a SV analysis. Its results are available via browser from control room PC's and are updated every 30 minutes, allowing to monitor the system security levels and to take suitable remedial actions to prevent a voltage collapse situation. The need to develop a process to identify voltage collapse situations in the Portuguese Transmission System arose with voltage problems identified in a specific substation when performing N-l contingency analysis. The operator training simulator, an important tool to analyse and understand the power system behaviour, was also used to study and demonstrate the voltage collapse phenomenon.