Research On The Nonlinear Characteristic Curves And Operational Characteristics Of Pumped Storage Units

Pumped storage units plays an important role on safe and stable operation of electric power system, as it can reduce peak, fill valley, modulate frequency and phase. This paper takes 250MW pumped storage units as the research object, established its steady finite element model and Field-Circuit-Network coupled Time-stepping FEM, systematically studied the nonlinear characteristic curves of pumped storage unit and operational characteristics under different working conditions. This study provides theoretical and practical reference for the design and normal operation of the pumped storage units. The main works are as follows:1. Respectively studied the field currents impact on the no-load voltage waveform and harmonic of pumped storage units under the consideration of magnetic saturation or not, results showed that when considering magnetic saturation, the voltage distortion rate and the harmonic content produced by the same field are larger.2. Studied the nonlinear characteristic curves of 250MW pumped storage generator under d-axis, q-axis and different angle operating conditions by adopting the combination of theoretical analysis and FEM. Found that with the increasing of angle, the nonlinear characteristic curves move to the lower right, and it moves when the field current adds. The magnetic field for the same voltage under the condition of load operation is different to the traditional no-load characteristic.3. Researched on the reactive power regulation characteristics of 250MW pumped storage units under the condition of considering magnetic saturation, contrast analysis of the stator current, reactive power, power factor and power angle changes with the field current when the units works under power generation condition and electric conditions. Analysis show that compared with the V-shaped curve without considering magnetic saturation, considering magnetic saturation will cause the V-shaped curve moves to the right shift obviously when the units running in the late phase area.4. Studied the large disturbance characteristics of the pumped storage units under the working condition of power generation and electric characteristics with the Field-Circuit-Network coupled Time-stepping FEM, get the current curve when the units running in the normal operation and the power line three-phase short circuit to ground condition.