VARIABLE SPEED HYDROPOWER PLANT WITH VIRTUAL INERTIA CONTROL FOR PROVISION OF FAST FREQUENCY RESERVES

摘要

Variable speed hydropower (VSHP) is well suited for virtual inertia (Ⅵ) control as it can utilize the kinetic energy of the turbine and generator to provide a fast power response to a frequency deviation. Moreover, governor control of the turbine can effectively regain the optimal turbine rotational speed. Despite this advantage, no investigation into different Ⅵ control structures for VSHP has been performed previously. In this paper, the results of dynamic simulations and eigenvalue analysis show that all five tested control structures deliver fast power reserves to maintain grid stability. The Ⅵ controllers based on the virtual synchronous machine (VSM) algorithm provide the best response in terms of inertia; however, a proportional controller must also be added to provide frequency containment reserves (FCRs). The virtual synchronous generator (VSG) is concluded to be the overall best alternative. It is better at reducing frequency deviations, provides fast frequency reserves (FFRs), and contributes more effectively to power oscillation damping in the two-area power system. The behaviour of the hydraulic system is similar for all Ⅵ control structures. However, a more advanced control system is needed to optimize the internal control of the VSHP plant while considering the constraints of the hydraulic system.