Solving the under voltage problem in Sri Lankan national grid

Abstract

Voltage stability is concerned with the ability of a power system to maintain acceptable voltages at all busses in the system under normal conditions and after being subjected to a disturbance. A system enters a state of voltage instability when a disturbance, increase in load demand, or change in system condition causes a progressive and uncontrollable decline in voltage. Voltage stability problems normally occur in heavily stressed systems. In addition to the strength of the transmission network and power transfer levels , the - principle factors contributing to the voltage collapse are the generator reactive power I voltage control limits, load characteristics , characteristics of reactive compensation devices, and the action of voltage control devices such as On Load Tap Changers (OL TCs). [1] Again low voltage can be associated with the process of rotor angle going out of step, but the type of voltage collapse related to voltage instability can occur where angle stability is not an issue. The gradual pulling out of step of machines , as rotor angles between two groups of machines approach or exceed 180° , results in very low voltage at intermediate positions in the network. However, in such cases the low voltage is a result of the rotor falling out of step rather than a cause of it. This research project is a dynamic approach to the voltage stability of an existing system considering the characteristics of transmission system and examining how the phenomenon is influenced by the characteristics of generators, loads and reactive power compensation devices .