Design and Development of a Scaled Prototype of a 250 MW Hydrogenerator Fed 765 kV Transmission Lines to Test Sub-Synchronous Oscillation in Power System Laboratory

The aim of this paper is to create a scaled-down model of a 765 kV extra high voltage (EHV) series compensated transmission line to test for sub-synchronous oscillations (SSO) in a hydropower system. The doubly fed induction machine (DFIM) with multi-megawatt power converters is typically adopted in large rated variable speed pumped storage power plants (VSP-SPPs) because it provides greater energy efficiency at wide changes in water head and surplus power availability, reduced cost and grid stability. The rotor excitation of the DFIM is handled by partial rated power converters, which manage the bulk excitation current (e.g. a typical 250 MW DFIM handles 11 620 A in rotor circuit). Parallel linked power converters are used due to the restricted power handling capability of semiconductor devices. Because the generating unit is asynchronous, any faults in the excitation system cause the generating unit's functioning to be disrupted. The suggested systems detect SSO with DFIM-based 765kv extra high voltage (EHV) series compensated transmission line is tested in the time domain MATLAB Simulink environment. A practical demonstration is carried out in the laboratory to scale down the transmission line model and check SSO in the DFIM system.