In the recent decade, temporary frequency support derived from variable speed wind turbine generator has been drawing increasing attention in the electronic-growing power system. Frequency nadir and rate of change of frequency are two key indicators temporary frequency support strives to improve. This paper proposes a novel insight on frequency regulation of wind power. Note that considerable part of load is shared by synchronous generators and wind turbine generator and the system frequency

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... ll will be dominated by the former for a period of time. Simultaneously taking the frequency regulation characteristic of synchronous and power balance into account, a novel frequency regulation scheme aiming at improving system's frequency regulation performance is proposed and tested in a 7-machine power system with an aggregated wind farm on MATLAB/Simulink to investigate what inherently determines the performance of frequency regulation. Results show that with differential cooperation of synchronous generator and doubly fed induction generator, frequency nadir and rate of change of frequency can be partially improved. Particularly, regarding to handling the issue of control delay, an appropriately slower action upon detecting a frequency event may not screw up it but contribute to a higher frequency nadir, which benefits from the spontaneous cooperation of synchronous generator and wind power with constraint of power balance. K E Y W O R D S cooperation control, doubly fed induction generator, inertia control, temporary frequency support, wind power | INTRODUCTION Conventionally, when a frequency event occurs, synchronous generators (SGs) intrinsically release kinetic energy (KE) as an inertial response; then, their primary and secondary controls can be used to restore the frequency. 1 However, the KE of variable speed wind turbine generator (VSWTG) is completely hidden by the converter, 2 and the wind power penetration (WPP) is increasing, reducing the installation of SG and frequency regulation capability of power system. If system frequency drops below the threshold of low-frequency load shedding relay, it will be activated to prevent frequency collapse. 3 Energy storage system is suitable for suppressing fluctuating power and maintaining system frequency stability. While considering the high cost, it is not that economical for large-capacity configuration. Conversely, the response from a VSWTG can be several times more per megawatt than that is observed for the primary response from an SG. 4 So it is promising to enhance the stable and economic operation of system by utilizing the rapid adjustable energy derived from rotor speed variation of wind turbine. 5