Frequency stability support requirements for WTs in slow-response thermal power systems

A review of the latest publications and updates of international grid codes shows that the future trend regarding frequency stability support by wind turbines (WTs) during disturbances will be to impose stringent requirements. Nevertheless, system dynamic response depends in a complex manner on wind power network development and power system characteristics and therefore, no general conclusions for all power systems can be made. This paper presents a comprehensive analysis of main effects of modern WTs able to support frequency stability on the dynamic performance of slow-response isolated thermal power systems. A general roadmap including key factors to consider for the determination of proper grid requirements for WTs is presented. The study is carried out for different wind power penetration levels and strategies for frequency support by WTs. The investigation is applied on the isolated power system in Northern Chile characterized by a thermal generation matrix with slow response generation units. Simulation results indicate that the adoption of severe grid requirements regarding frequency stability support by WTs is already justified for penetration levels above 5%, in which case the system performance even improves compared to the scenario without wind power.