Mitigating system´s voltage instability through wide-area early warning signals and real-time HVDC control

Two sequential approaches to prevent voltage instability are proposed in this article. The first approach utilizes synchrophasors in order to establish when the system is leading to a voltage instability and also to trigger the operation of HVDCs to relieve the system´s stress. The second approach is used to ensure that HVDCs will operate securely when their transfer is pushed towards the maximum transferable power level.