Study on frequency control strategy for ORMOC-NAGA HVDC project in Philippines

This paper introduces the refurbishment of ORMOC-NAGA High Voltage Direct Current (ORMOC-NAGA HVDC)transmission project in Philippines, and presents the improvements of control & protection system for ORMOC-NAGA HVDC project. The problem of the frequency stability in Visayas grid is analyzed. Considering the characteristics of the HVDC link bidirectional operation and the unreliable telecommunication, a frequency control strategy independent of the direction of power flow from the link is proposed. The performance of the frequency controller in the normal power direction and reverse power direction is analyzed and the frequency control strategy for the telecommunication failure is discussed. Furthermore, the coordination of the frequency controller in ORMOC station and the emergency power controller in NAGA station is also discussed. Finally, the function and performance of the proposed control strategies were verified by commissioning test. The adoption of these strategies effectively increases the stability and reliability of the Visayas and Luzon power grid.