Strategy of Active and Reactive Power Inter-coordination Control Among HVDCs

A new emergency DC power supply (EDCPS) control strategy for multi DC system is presented to improve system stability, when a fault results in one DC system blocked. Furthermore, a coordination control strategy for reactive power among HVDC converter stations is put forward in concert with EDCPS. An important feature of the method proposed is that it makes full use of the available AC filters of the outage HVDC system to meet the increasing reactive power demand of adjacent DC system running with EDCPS. The simulation results of a testing system with one AC and three DC lines in parallel in PSCAD/EMTDC show that the control strategy can significantly improve the frequency and voltage stability.