Application of Point on Wave Controlled Switching on High Voltage Systems for Weak Offshore Grids

Abstract

At offshore oil and gas islands, on site generators running independently are often utilized. These on site generators have their benefits but also pose their own drawbacks and may have their own problems. Due to the instability of those weak offshore grids, the grid disturbances may cause power outages, voltage fluctuations, changes in frequency, blackouts …etc. which are easily felt by the consumers and can also impact the performance and the service life of the electrical equipment. A study has been performed to examine different methods to improve the reliability of the overall network. Circuit breakers are designed to react by opening or closing the circuit as soon as a command is received. While doing so, the circuit breakers go through tremendous high stresses which ultimately may cause it to produce an arc. This phenomenon can be mitigated and reduced using controlled switching. This technology involves pre-defined control strategy for opening and closing each circuit breaker pole independently. Controlled switching methodologies are used to minimize the stress on circuit breakers, prevent failure of electrical equipment and improve power quality without affecting the overall grid. This new cost effective technology helps in reducing disturbances while improving electrical reliability to the end consumer. High Voltage Shunt Reactors, Subsea Cables and Transformer Energization and De-energization cause high inrush current on the system. Power system study software has been utilized to identify which loads will provide the optimum benefit when implementing the Controlled Switching application. This paper addresses the benefits of using controlled switching on high voltage circuit breakers on weak offshore grids. This paper also studies the applications and advantages of controlled switching of 132kV long subsea cable and transformer feeders wherein high inrush current is expected while showing the outcomes of research results and actual scenarios that have been implemented