Frequency dynamics during high CCGT and wind penetrations

Frequency stability is the paramount concern for secure and reliable operation of a power system. High wind penetration levels are reported in power systems with high thermal generation, and hence its likely to result high wind and combined-cycle gas turbine (CCGT) penetrations during system operation since CCGTs are the most preferable choice for the thermal generation. The doubly-fed induction generators (DFIGs) do not provide any inertial response while the CCGTs have unique frequency response during the system frequency disturbances. Therefore, CCGT turbine response characteristics and the zero inertial response may influence on frequency dynamics of a power network. The main objective of this study is to analyze the frequency dynamics during generator outages and three-phase short-circuit faults in a power network with high CCGT and wind penetrations. A test network model was developed based on the Northern-Ireland network in DIgSILENT Power Factory software package. It has shown that frequency stability may be threatened when three-phase short circuit faults occur in power networks during high CCGT and wind penetrations which may lead to CCGT combustor lean-blowout and ultimately results large frequency excursions in the network.